51518758661 has 2 divisors, whose sum is σ = 51518758662. Its totient is φ = 51518758660.

The previous prime is 51518758637. The next prime is 51518758693. The reversal of 51518758661 is 16685781515.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43576562500 + 7942196161 = 208750^2 + 89119^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51518758661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51518758601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25759379330 + 25759379331.

It is an arithmetic number, because the mean of its divisors is an integer number (25759379331).

Almost surely, 2^51518758661 is an apocalyptic number.

It is an amenable number.

51518758661 is a deficient number, since it is larger than the sum of its proper divisors (1).

51518758661 is an equidigital number, since it uses as much as digits as its factorization.

51518758661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016000, while the sum is 53.

The spelling of 51518758661 in words is "fifty-one billion, five hundred eighteen million, seven hundred fifty-eight thousand, six hundred sixty-one".