252638721 has 6 divisors (see below), whose sum is σ = 364922610. Its totient is φ = 168425808.

The previous prime is 252638719. The next prime is 252638723. The reversal of 252638721 is 127836252.

252638721 is a `hidden beast` number, since 252 + 6 + 387 + 21 = 666.

252638721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (252638719) and next prime (252638723).

It can be written as a sum of positive squares in only one way, i.e., 242238096 + 10400625 = 15564^2 + 3225^2 .

It is not a de Polignac number, because 252638721 - 2¹ = 252638719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (252638723) 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, 14035476 + ... + 14035493.

It is an arithmetic number, because the mean of its divisors is an integer number (60820435).

Almost surely, 2^252638721 is an apocalyptic number.

It is an amenable number.

252638721 is a deficient number, since it is larger than the sum of its proper divisors (112283889).

252638721 is a wasteful number, since it uses less digits than its factorization.

252638721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28070975 (or 28070972 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 252638721 is about 15894.6129553380. The cubic root of 252638721 is about 632.1691592071.

The spelling of 252638721 in words is "two hundred fifty-two million, six hundred thirty-eight thousand, seven hundred twenty-one".