• 89 can be written using four 4's:

89 has 2 divisors, whose sum is σ = 90. Its totient is φ = 88.

The previous prime is 83. The next prime is 97. The reversal of 89 is 98.

It is the 10-th Fibonacci number F_{10}.

89 is nontrivially palindromic in base 8.

89 is an esthetic number in base 10 and base 14, because in such bases its adjacent digits differ by 1.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64 + 25 = 8^2 + 5^2 .

It is a cyclic number.

It is not a de Polignac number, because 89 - 2^{4} = 73 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a magnanimous number.

It is a d-powerful number, because it can be written as **9**^{2} + **8** .

It is an alternating number because its digits alternate between even and odd.

89 is an undulating number in base 8.

89 is a modest number, since divided by 9 gives 8 as remainder.

It is a Curzon number.

It is a plaindrome in base 6, base 7, base 10, base 13, base 15 and base 16.

It is a nialpdrome in base 11, base 12 and base 14.

It is a panconsummate number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 44 + 45.

It is an arithmetic number, because the mean of its divisors is an integer number (45).

It is an amenable number.

89 is a deficient number, since it is larger than the sum of its proper divisors (1).

89 is an equidigital number, since it uses as much as digits as its factorization.

89 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72, while the sum is 17.

The square root of 89 is about 9.4339811321. The cubic root of 89 is about 4.4647450956.

Adding to 89 its product of digits (72), we get a palindrome (161).

The spelling of 89 in words is "eighty-nine", and thus it is an aban number, an oban number, and an uban number.

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