51115511550 has 48 divisors (see below), whose sum is σ = 126830690352. Its totient is φ = 13623897600.

The previous prime is 51115511519. The next prime is 51115511567. The reversal of 51115511550 is 5511551115.

It is a happy number.

It is a super-2 number, since 2×51115511550² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 214230 + ... + 384870.

It is an arithmetic number, because the mean of its divisors is an integer number (2642306049).

Almost surely, 2^51115511550 is an apocalyptic number.

51115511550 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

51115511550 is an abundant number, since it is smaller than the sum of its proper divisors (75715178802).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51115511550 is a wasteful number, since it uses less digits than its factorization.

51115511550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172653 (or 172648 counting only the distinct ones).

The product of its (nonzero) digits is 3125, while the sum is 30.

The spelling of 51115511550 in words is "fifty-one billion, one hundred fifteen million, five hundred eleven thousand, five hundred fifty".