90989999 has 4 divisors (see below), whose sum is σ = 91391064. Its totient is φ = 90588936.

The previous prime is 90989989. The next prime is 90990007. The reversal of 90989999 is 99998909.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-90989999 is a prime.

It is a Duffinian number.

90989999 is a modest number, since divided by 9999 gives 9098 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90989939) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 200192 + ... + 200645.

It is an arithmetic number, because the mean of its divisors is an integer number (22847766).

Almost surely, 2^90989999 is an apocalyptic number.

90989999 is a deficient number, since it is larger than the sum of its proper divisors (401065).

90989999 is a wasteful number, since it uses less digits than its factorization.

90989999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401064.

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

The square root of 90989999 is about 9538.8678049337. The cubic root of 90989999 is about 449.7776663003. Note that the first 3 decimals are identical.

The spelling of 90989999 in words is "ninety million, nine hundred eighty-nine thousand, nine hundred ninety-nine".