51536721 has 24 divisors (see below), whose sum is σ = 75712320. Its totient is φ = 31119264.

The previous prime is 51536711. The next prime is 51536729. The reversal of 51536721 is 12763515.

It is not a de Polignac number, because 51536721 - 2⁵ = 51536689 is a prime.

It is a super-2 number, since 2×51536721² = 5312067222863682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51536729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23875 + ... + 25943.

It is an arithmetic number, because the mean of its divisors is an integer number (3154680).

Almost surely, 2^51536721 is an apocalyptic number.

It is an amenable number.

51536721 is a deficient number, since it is larger than the sum of its proper divisors (24175599).

51536721 is a wasteful number, since it uses less digits than its factorization.

51536721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2133 (or 2114 counting only the distinct ones).

The product of its digits is 6300, while the sum is 30.

The square root of 51536721 is about 7178.9080646015. The cubic root of 51536721 is about 372.1393497476.

The spelling of 51536721 in words is "fifty-one million, five hundred thirty-six thousand, seven hundred twenty-one".