51213725621 has 6 divisors (see below), whose sum is σ = 51501466422. Its totient is φ = 50927583560.

The previous prime is 51213725603. The next prime is 51213725623. The reversal of 51213725621 is 12652731215.

It can be written as a sum of positive squares in only one way, i.e., 48790624996 + 2423100625 = 220886^2 + 49225^2 .

It is not a de Polignac number, because 51213725621 - 2⁶ = 51213725557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51213725623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 767150 + ... + 831231.

It is an arithmetic number, because the mean of its divisors is an integer number (8583577737).

Almost surely, 2^51213725621 is an apocalyptic number.

It is an amenable number.

51213725621 is a deficient number, since it is larger than the sum of its proper divisors (287740801).

51213725621 is an equidigital number, since it uses as much as digits as its factorization.

51213725621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1598739 (or 1598560 counting only the distinct ones).

The product of its digits is 25200, while the sum is 35.

The spelling of 51213725621 in words is "fifty-one billion, two hundred thirteen million, seven hundred twenty-five thousand, six hundred twenty-one".