20517120621 has 12 divisors (see below), whose sum is σ = 29832106720. Its totient is φ = 13587496200.

The previous prime is 20517120563. The next prime is 20517120623. The reversal of 20517120621 is 12602171502.

20517120621 is a `hidden beast` number, since 2 + 0 + 5 + 17 + 1 + 20 + 621 = 666.

It is not a de Polignac number, because 20517120621 - 2⁹ = 20517120109 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20517120623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7547251 + ... + 7549968.

Almost surely, 2^20517120621 is an apocalyptic number.

It is an amenable number.

20517120621 is a deficient number, since it is larger than the sum of its proper divisors (9314986099).

20517120621 is a wasteful number, since it uses less digits than its factorization.

20517120621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15097376 (or 15097373 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The spelling of 20517120621 in words is "twenty billion, five hundred seventeen million, one hundred twenty thousand, six hundred twenty-one".