251373537261 has 144 divisors (see below), whose sum is σ = 477421439040. Its totient is φ = 125880168960.

The previous prime is 251373537209. The next prime is 251373537299. The reversal of 251373537261 is 162735373152.

251373537261 is a `hidden beast` number, since 2 + 5 + 1 + 37 + 353 + 7 + 261 = 666.

It is not a de Polignac number, because 251373537261 - 2⁶ = 251373537197 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251373532261) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 131815270 + ... + 131817176.

It is an arithmetic number, because the mean of its divisors is an integer number (3315426660).

Almost surely, 2^251373537261 is an apocalyptic number.

251373537261 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

251373537261 is a deficient number, since it is larger than the sum of its proper divisors (226047901779).

251373537261 is a wasteful number, since it uses less digits than its factorization.

251373537261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2904 (or 2894 counting only the distinct ones).

The product of its digits is 793800, while the sum is 45.

The spelling of 251373537261 in words is "two hundred fifty-one billion, three hundred seventy-three million, five hundred thirty-seven thousand, two hundred sixty-one".