631817521920 has 1440 divisors, whose sum is σ = 2580281827200. Its totient is φ = 146448580608.

The previous prime is 631817521903. The next prime is 631817521963. The reversal of 631817521920 is 29125718136.

631817521920 is a `hidden beast` number, since 6 + 31 + 8 + 1 + 7 + 521 + 92 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1440).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 2759028366 + ... + 2759028594.

It is an arithmetic number, because the mean of its divisors is an integer number (1791862380).

Almost surely, 2^631817521920 is an apocalyptic number.

631817521920 is a gapful number since it is divisible by the number (60) 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 631817521920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1290140913600).

631817521920 is an abundant number, since it is smaller than the sum of its proper divisors (1948464305280).

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

631817521920 is a wasteful number, since it uses less digits than its factorization.

631817521920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387 (or 364 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 45.

The spelling of 631817521920 in words is "six hundred thirty-one billion, eight hundred seventeen million, five hundred twenty-one thousand, nine hundred twenty".