51131691 has 24 divisors (see below), whose sum is σ = 83000736. Its totient is φ = 30096000.

The previous prime is 51131677. The next prime is 51131693. The reversal of 51131691 is 19613115.

It is not a de Polignac number, because 51131691 - 2¹⁷ = 51000619 is a prime.

It is a super-2 number, since 2×51131691² = 5228899649038962, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51131693) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6810 + ... + 12191.

It is an arithmetic number, because the mean of its divisors is an integer number (3458364).

Almost surely, 2^51131691 is an apocalyptic number.

51131691 is a deficient number, since it is larger than the sum of its proper divisors (31869045).

51131691 is a wasteful number, since it uses less digits than its factorization.

51131691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19043 (or 19040 counting only the distinct ones).

The product of its digits is 810, while the sum is 27.

The square root of 51131691 is about 7150.6426983873. The cubic root of 51131691 is about 371.1618965848.

The spelling of 51131691 in words is "fifty-one million, one hundred thirty-one thousand, six hundred ninety-one".