51331491 has 6 divisors (see below), whose sum is σ = 74145500. Its totient is φ = 34220988.

The previous prime is 51331481. The next prime is 51331499. The reversal of 51331491 is 19413315.

51331491 is a `hidden beast` number, since 513 + 3 + 149 + 1 = 666.

It is not a de Polignac number, because 51331491 - 2⁵ = 51331459 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51331499) 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, 2851741 + ... + 2851758.

Almost surely, 2^51331491 is an apocalyptic number.

51331491 is a deficient number, since it is larger than the sum of its proper divisors (22814009).

51331491 is a wasteful number, since it uses less digits than its factorization.

51331491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5703505 (or 5703502 counting only the distinct ones).

The product of its digits is 1620, while the sum is 27.

The square root of 51331491 is about 7164.5998492589. The cubic root of 51331491 is about 371.6447136807.

The spelling of 51331491 in words is "fifty-one million, three hundred thirty-one thousand, four hundred ninety-one".