51931136581 has 2 divisors, whose sum is σ = 51931136582. Its totient is φ = 51931136580.

The previous prime is 51931136573. The next prime is 51931136611. The reversal of 51931136581 is 18563113915.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49922752356 + 2008384225 = 223434^2 + 44815^2 .

It is a cyclic number.

It is not a de Polignac number, because 51931136581 - 2³ = 51931136573 is a prime.

It is a super-2 number, since 2×51931136581² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51931136501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25965568290 + 25965568291.

It is an arithmetic number, because the mean of its divisors is an integer number (25965568291).

Almost surely, 2^51931136581 is an apocalyptic number.

It is an amenable number.

51931136581 is a deficient number, since it is larger than the sum of its proper divisors (1).

51931136581 is an equidigital number, since it uses as much as digits as its factorization.

51931136581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 97200, while the sum is 43.

The spelling of 51931136581 in words is "fifty-one billion, nine hundred thirty-one million, one hundred thirty-six thousand, five hundred eighty-one".