20556620521 has 8 divisors (see below), whose sum is σ = 21231385088. Its totient is φ = 19882584000.

The previous prime is 20556620489. The next prime is 20556620533. The reversal of 20556620521 is 12502665502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20556620521 - 2⁵ = 20556620489 is a prime.

It is a super-2 number, since 2×20556620521² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20556620551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 124320 + ... + 237841.

It is an arithmetic number, because the mean of its divisors is an integer number (2653923136).

Almost surely, 2^20556620521 is an apocalyptic number.

It is an amenable number.

20556620521 is a deficient number, since it is larger than the sum of its proper divisors (674764567).

20556620521 is a wasteful number, since it uses less digits than its factorization.

20556620521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364023.

The product of its (nonzero) digits is 36000, while the sum is 34.

The spelling of 20556620521 in words is "twenty billion, five hundred fifty-six million, six hundred twenty thousand, five hundred twenty-one".