251532551421 has 40 divisors (see below), whose sum is σ = 378435123000. Its totient is φ = 166489344000.

The previous prime is 251532551399. The next prime is 251532551467. The reversal of 251532551421 is 124155235152.

251532551421 is a `hidden beast` number, since 2 + 51 + 5 + 32 + 551 + 4 + 21 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 10535996025 + 240996555396 = 102645^2 + 490914^2 .

It is a de Polignac number, because none of the positive numbers 2^k-251532551421 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 (251532551471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 48285465 + ... + 48290673.

It is an arithmetic number, because the mean of its divisors is an integer number (9460878075).

Almost surely, 2^251532551421 is an apocalyptic number.

It is an amenable number.

251532551421 is a deficient number, since it is larger than the sum of its proper divisors (126902571579).

251532551421 is a wasteful number, since it uses less digits than its factorization.

251532551421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9371 (or 9362 counting only the distinct ones).

The product of its digits is 60000, while the sum is 36.

Adding to 251532551421 its reverse (124155235152), we get a palindrome (375687786573).

The spelling of 251532551421 in words is "two hundred fifty-one billion, five hundred thirty-two million, five hundred fifty-one thousand, four hundred twenty-one".