20557630251 has 16 divisors (see below), whose sum is σ = 30459413920. Its totient is φ = 13703437440.

The previous prime is 20557630231. The next prime is 20557630259. The reversal of 20557630251 is 15203675502.

20557630251 is a `hidden beast` number, since 2 + 0 + 5 + 576 + 30 + 2 + 51 = 666.

It is not a de Polignac number, because 20557630251 - 2³³ = 11967695659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20557630259) 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, 208311 + ... + 290703.

It is an arithmetic number, because the mean of its divisors is an integer number (1903713370).

Almost surely, 2^20557630251 is an apocalyptic number.

20557630251 is a deficient number, since it is larger than the sum of its proper divisors (9901783669).

20557630251 is an equidigital number, since it uses as much as digits as its factorization.

20557630251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91643 (or 91637 counting only the distinct ones).

The product of its (nonzero) digits is 63000, while the sum is 36.

The spelling of 20557630251 in words is "twenty billion, five hundred fifty-seven million, six hundred thirty thousand, two hundred fifty-one".