51005555557 has 6 divisors (see below), whose sum is σ = 56063957894. Its totient is φ = 46368686760.

The previous prime is 51005555551. The next prime is 51005555567. The reversal of 51005555557 is 75555550015.

It can be written as a sum of positive squares in only one way, i.e., 32978196801 + 18027358756 = 181599^2 + 134266^2 .

It is not a de Polignac number, because 51005555557 - 2⁷ = 51005555429 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 (51005555551) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 210766638 + ... + 210766879.

Almost surely, 2^51005555557 is an apocalyptic number.

It is an amenable number.

51005555557 is a deficient number, since it is larger than the sum of its proper divisors (5058402337).

51005555557 is a wasteful number, since it uses less digits than its factorization.

51005555557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 421533539 (or 421533528 counting only the distinct ones).

The product of its (nonzero) digits is 546875, while the sum is 43.

The spelling of 51005555557 in words is "fifty-one billion, five million, five hundred fifty-five thousand, five hundred fifty-seven".