90999989 has 2 divisors, whose sum is σ = 90999990. Its totient is φ = 90999988.

The previous prime is 90999977. The next prime is 91000009. The reversal of 90999989 is 98999909.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 86304100 + 4695889 = 9290^2 + 2167^2 .

It is a cyclic number.

It is not a de Polignac number, because 90999989 - 2¹² = 90995893 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90999959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45499994 + 45499995.

It is an arithmetic number, because the mean of its divisors is an integer number (45499995).

Almost surely, 2^90999989 is an apocalyptic number.

It is an amenable number.

90999989 is a deficient number, since it is larger than the sum of its proper divisors (1).

90999989 is an equidigital number, since it uses as much as digits as its factorization.

90999989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4251528, while the sum is 62.

The square root of 90999989 is about 9539.3914376128. The cubic root of 90999989 is about 449.7941264040.

The spelling of 90999989 in words is "ninety million, nine hundred ninety-nine thousand, nine hundred eighty-nine".