51261940921 has 9 divisors (see below), whose sum is σ = 51484558671. Its totient is φ = 51040284552.

The previous prime is 51261940901. The next prime is 51261940957. The reversal of 51261940921 is 12904916215.

The square root of 51261940921 is 226411.

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

It can be written as a sum of positive squares in only one way, i.e., 27863955625 + 23397985296 = 166925^2 + 152964^2 .

It is a de Polignac number, because none of the positive numbers 2^k-51261940921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51261940901) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 84451000 + ... + 84451606.

It is an arithmetic number, because the mean of its divisors is an integer number (5720506519).

Almost surely, 2^51261940921 is an apocalyptic number.

51261940921 is the 226411-st square number.

51261940921 is the 113206-th centered octagonal number.

It is an amenable number.

51261940921 is a deficient number, since it is larger than the sum of its proper divisors (222617750).

51261940921 is an frugal number, since it uses more digits than its factorization.

51261940921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1960 (or 980 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 40.

The spelling of 51261940921 in words is "fifty-one billion, two hundred sixty-one million, nine hundred forty thousand, nine hundred twenty-one".