90909999 has 64 divisors (see below), whose sum is σ = 150698880. Its totient is φ = 53913600.

The previous prime is 90909991. The next prime is 90910009. The reversal of 90909999 is 99990909.

It is not a de Polignac number, because 90909999 - 2³ = 90909991 is a prime.

90909999 is a modest number, since divided by 9999 gives 9090 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90909991) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 900049 + ... + 900149.

It is an arithmetic number, because the mean of its divisors is an integer number (2354670).

Almost surely, 2^90909999 is an apocalyptic number.

90909999 is a deficient number, since it is larger than the sum of its proper divisors (59788881).

90909999 is a wasteful number, since it uses less digits than its factorization.

90909999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217 (or 211 counting only the distinct ones).

The product of its (nonzero) digits is 531441, while the sum is 54.

The square root of 90909999 is about 9534.6735130260. The cubic root of 90909999 is about 449.6458101833.

The spelling of 90909999 in words is "ninety million, nine hundred nine thousand, nine hundred ninety-nine".