15666115600981 has 2 divisors, whose sum is σ = 15666115600982. Its totient is φ = 15666115600980.

The previous prime is 15666115600871. The next prime is 15666115601011. The reversal of 15666115600981 is 18900651166651.

15666115600981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12519071532900 + 3147044068081 = 3538230^2 + 1773991^2 .

It is a cyclic number.

It is not a de Polignac number, because 15666115600981 - 2¹⁷ = 15666115469909 is a prime.

It is a super-2 number, since 2×15666115600981² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15666115600081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7833057800490 + 7833057800491.

It is an arithmetic number, because the mean of its divisors is an integer number (7833057800491).

Almost surely, 2^{15666115600981} is an apocalyptic number.

It is an amenable number.

15666115600981 is a deficient number, since it is larger than the sum of its proper divisors (1).

15666115600981 is an equidigital number, since it uses as much as digits as its factorization.

15666115600981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2332800, while the sum is 55.

The spelling of 15666115600981 in words is "fifteen trillion, six hundred sixty-six billion, one hundred fifteen million, six hundred thousand, nine hundred eighty-one".