251190413721 has 81 divisors (see below), whose sum is σ = 400712952861. Its totient is φ = 151559553600.

The previous prime is 251190413693. The next prime is 251190413723. The reversal of 251190413721 is 127314091152.

It is a happy number.

The square root of 251190413721 is 501189.

It is a perfect power (a square), and thus also a powerful number.

251190413721 is a `hidden beast` number, since 2 + 51 + 190 + 413 + 7 + 2 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 193463624025 + 57726789696 = 439845^2 + 240264^2 .

It is not a de Polignac number, because 251190413721 - 2⁹ = 251190413209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (251190413723) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 1387792251 + ... + 1387792431.

Almost surely, 2^251190413721 is an apocalyptic number.

251190413721 is the 501189-th square number.

251190413721 is the 250595-th centered octagonal number.

It is an amenable number.

251190413721 is a deficient number, since it is larger than the sum of its proper divisors (149522539140).

251190413721 is an equidigital number, since it uses as much as digits as its factorization.

251190413721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 536 (or 268 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 36.

Multiplying 251190413721 by its sum of digits (36), we get a square (9042854893956 = 3007134²).

The spelling of 251190413721 in words is "two hundred fifty-one billion, one hundred ninety million, four hundred thirteen thousand, seven hundred twenty-one".