20931240521664 has 448 divisors, whose sum is σ = 68812000104960. Its totient is φ = 6183889920000.

The previous prime is 20931240521647. The next prime is 20931240521683. The reversal of 20931240521664 is 46612504213902.

20931240521664 is a `hidden beast` number, since 20 + 9 + 3 + 1 + 2 + 40 + 521 + 6 + 64 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1257047739 + ... + 1257064389.

It is an arithmetic number, because the mean of its divisors is an integer number (153598214520).

Almost surely, 2^{20931240521664} is an apocalyptic number.

20931240521664 is a gapful number since it is divisible by the number (24) 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 20931240521664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34406000052480).

20931240521664 is an abundant number, since it is smaller than the sum of its proper divisors (47880759583296).

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

20931240521664 is a wasteful number, since it uses less digits than its factorization.

20931240521664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18337 (or 18321 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The spelling of 20931240521664 in words is "twenty trillion, nine hundred thirty-one billion, two hundred forty million, five hundred twenty-one thousand, six hundred sixty-four".