251551399401 has 27 divisors (see below), whose sum is σ = 375520783287. Its totient is φ = 162261132480.

The previous prime is 251551399367. The next prime is 251551399453. The reversal of 251551399401 is 104993155152.

The square root of 251551399401 is 501549.

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

251551399401 is a `hidden beast` number, since 2 + 5 + 1 + 5 + 513 + 99 + 40 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 239752226025 + 11799173376 = 489645^2 + 108624^2 .

It is not a de Polignac number, because 251551399401 - 2¹³ = 251551391209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (251551399471) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 46641361 + ... + 46646753.

Almost surely, 2^251551399401 is an apocalyptic number.

251551399401 is the 501549-th square number.

251551399401 is the 250775-th centered octagonal number.

It is an amenable number.

251551399401 is a deficient number, since it is larger than the sum of its proper divisors (123969383886).

251551399401 is an frugal number, since it uses more digits than its factorization.

251551399401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10854 (or 5427 counting only the distinct ones).

The product of its (nonzero) digits is 243000, while the sum is 45.

The spelling of 251551399401 in words is "two hundred fifty-one billion, five hundred fifty-one million, three hundred ninety-nine thousand, four hundred one".