990639868 has 24 divisors (see below), whose sum is σ = 1813702464. Its totient is φ = 472953600.

The previous prime is 990639863. The next prime is 990639869. The reversal of 990639868 is 868936099.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990639863) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56553 + ... + 71968.

It is an arithmetic number, because the mean of its divisors is an integer number (75570936).

Almost surely, 2^990639868 is an apocalyptic number.

It is an amenable number.

990639868 is a deficient number, since it is larger than the sum of its proper divisors (823062596).

990639868 is a wasteful number, since it uses less digits than its factorization.

990639868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128613 (or 128611 counting only the distinct ones).

The product of its (nonzero) digits is 5038848, while the sum is 58.

The square root of 990639868 is about 31474.4319726345. The cubic root of 990639868 is about 996.8701703864.

The spelling of 990639868 in words is "nine hundred ninety million, six hundred thirty-nine thousand, eight hundred sixty-eight".