20555100557 has 4 divisors (see below), whose sum is σ = 20582471616. Its totient is φ = 20527729500.

The previous prime is 20555100539. The next prime is 20555100569. The reversal of 20555100557 is 75500155502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20555100557 - 2⁸ = 20555100301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20555109557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13684403 + ... + 13685904.

It is an arithmetic number, because the mean of its divisors is an integer number (5145617904).

Almost surely, 2^20555100557 is an apocalyptic number.

It is an amenable number.

20555100557 is a deficient number, since it is larger than the sum of its proper divisors (27371059).

20555100557 is an equidigital number, since it uses as much as digits as its factorization.

20555100557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27371058.

The product of its (nonzero) digits is 43750, while the sum is 35.

Subtracting 20555100557 from its reverse (75500155502), we obtain a palindrome (54945054945).

The spelling of 20555100557 in words is "twenty billion, five hundred fifty-five million, one hundred thousand, five hundred fifty-seven".