990921633840 has 120 divisors (see below), whose sum is σ = 3329807972400. Its totient is φ = 264089912832.

The previous prime is 990921633833. The next prime is 990921633851. The reversal of 990921633840 is 48336129099.

990921633840 is a `hidden beast` number, since 9 + 90 + 9 + 216 + 338 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 818254 + ... + 1628306.

It is an arithmetic number, because the mean of its divisors is an integer number (27748399770).

Almost surely, 2^990921633840 is an apocalyptic number.

990921633840 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 990921633840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1664903986200).

990921633840 is an abundant number, since it is smaller than the sum of its proper divisors (2338886338560).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

990921633840 is a wasteful number, since it uses less digits than its factorization.

990921633840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811771 (or 811762 counting only the distinct ones).

The product of its (nonzero) digits is 2519424, while the sum is 54.

The spelling of 990921633840 in words is "nine hundred ninety billion, nine hundred twenty-one million, six hundred thirty-three thousand, eight hundred forty".