20991825909936 has 120 divisors (see below), whose sum is σ = 67492044232704. Its totient is φ = 5966263105920.

The previous prime is 20991825909917. The next prime is 20991825909953. The reversal of 20991825909936 is 63990952819902.

20991825909936 is a `hidden beast` number, since 20 + 9 + 9 + 1 + 8 + 2 + 590 + 9 + 9 + 3 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 54323766 + ... + 54708821.

Almost surely, 2^{20991825909936} is an apocalyptic number.

It is an amenable number.

20991825909936 is an abundant number, since it is smaller than the sum of its proper divisors (46500218322768).

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

20991825909936 is a wasteful number, since it uses less digits than its factorization.

20991825909936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109032799 (or 109032790 counting only the distinct ones).

The product of its (nonzero) digits is 170061120, while the sum is 72.

The spelling of 20991825909936 in words is "twenty trillion, nine hundred ninety-one billion, eight hundred twenty-five million, nine hundred nine thousand, nine hundred thirty-six".