51326721 has 6 divisors (see below), whose sum is σ = 74138610. Its totient is φ = 34217808.

The previous prime is 51326719. The next prime is 51326729. The reversal of 51326721 is 12762315.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 34680321 + 16646400 = 5889^2 + 4080^2 .

It is not a de Polignac number, because 51326721 - 2¹ = 51326719 is a prime.

It is a super-2 number, since 2×51326721² = 5268864577223682, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51326729) 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, 2851476 + ... + 2851493.

It is an arithmetic number, because the mean of its divisors is an integer number (12356435).

Almost surely, 2^51326721 is an apocalyptic number.

It is an amenable number.

51326721 is a deficient number, since it is larger than the sum of its proper divisors (22811889).

51326721 is a wasteful number, since it uses less digits than its factorization.

51326721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5702975 (or 5702972 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 51326721 is about 7164.2669548252. The cubic root of 51326721 is about 371.6332015780.

The spelling of 51326721 in words is "fifty-one million, three hundred twenty-six thousand, seven hundred twenty-one".