51111990 has 48 divisors (see below), whose sum is σ = 133806816. Its totient is φ = 13536000.

The previous prime is 51111989. The next prime is 51112043. The reversal of 51111990 is 9911115.

51111990 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×51111990² = 5224871043520200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11710 + ... + 15470.

It is an arithmetic number, because the mean of its divisors is an integer number (2787642).

Almost surely, 2^51111990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51111990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (66903408).

51111990 is an abundant number, since it is smaller than the sum of its proper divisors (82694826).

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

51111990 is a wasteful number, since it uses less digits than its factorization.

51111990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3925 (or 3922 counting only the distinct ones).

The product of its (nonzero) digits is 405, while the sum is 27.

The square root of 51111990 is about 7149.2649971868. The cubic root of 51111990 is about 371.1142209996.

The spelling of 51111990 in words is "fifty-one million, one hundred eleven thousand, nine hundred ninety".