20565722421 has 16 divisors (see below), whose sum is σ = 30504880320. Its totient is φ = 13693767120.

The previous prime is 20565722413. The next prime is 20565722449. The reversal of 20565722421 is 12422756502.

20565722421 is a `hidden beast` number, since 2 + 0 + 565 + 72 + 2 + 4 + 21 = 666.

It is not a de Polignac number, because 20565722421 - 2³ = 20565722413 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20565722921) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 441715 + ... + 486048.

It is an arithmetic number, because the mean of its divisors is an integer number (1906555020).

Almost surely, 2^20565722421 is an apocalyptic number.

It is an amenable number.

20565722421 is a deficient number, since it is larger than the sum of its proper divisors (9939157899).

20565722421 is an equidigital number, since it uses as much as digits as its factorization.

20565722421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 928593 (or 928587 counting only the distinct ones).

The product of its (nonzero) digits is 67200, while the sum is 36.

The spelling of 20565722421 in words is "twenty billion, five hundred sixty-five million, seven hundred twenty-two thousand, four hundred twenty-one".