51013191321 has 27 divisors (see below), whose sum is σ = 74708651199. Its totient is φ = 33543068832.

The previous prime is 51013191319. The next prime is 51013191349. The reversal of 51013191321 is 12319131015.

It is a happy number.

The square root of 51013191321 is 225861.

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

51013191321 is a `hidden beast` number, since 510 + 1 + 3 + 19 + 132 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21244520025 + 29768671296 = 145755^2 + 172536^2 .

It is not a de Polignac number, because 51013191321 - 2¹ = 51013191319 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51013141321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 53528581 + ... + 53529533.

Almost surely, 2^51013191321 is an apocalyptic number.

51013191321 is the 225861-st square number.

51013191321 is the 112931-st centered octagonal number.

It is an amenable number.

51013191321 is a deficient number, since it is larger than the sum of its proper divisors (23695459878).

51013191321 is an frugal number, since it uses more digits than its factorization.

51013191321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2070 (or 1035 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 27.

The spelling of 51013191321 in words is "fifty-one billion, thirteen million, one hundred ninety-one thousand, three hundred twenty-one".