61516320565981 has 2 divisors, whose sum is σ = 61516320565982. Its totient is φ = 61516320565980.

The previous prime is 61516320565957. The next prime is 61516320566053. The reversal of 61516320565981 is 18956502361516.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48245665728100 + 13270654837881 = 6945910^2 + 3642891^2 .

It is a cyclic number.

It is not a de Polignac number, because 61516320565981 - 2⁵ = 61516320565949 is a prime.

It is a super-2 number, since 2×61516320565981² (a number of 28 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61516320565901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30758160282990 + 30758160282991.

It is an arithmetic number, because the mean of its divisors is an integer number (30758160282991).

Almost surely, 2^{61516320565981} is an apocalyptic number.

It is an amenable number.

61516320565981 is a deficient number, since it is larger than the sum of its proper divisors (1).

61516320565981 is an equidigital number, since it uses as much as digits as its factorization.

61516320565981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664000, while the sum is 58.

The spelling of 61516320565981 in words is "sixty-one trillion, five hundred sixteen billion, three hundred twenty million, five hundred sixty-five thousand, nine hundred eighty-one".