15915329981 has 2 divisors, whose sum is σ = 15915329982. Its totient is φ = 15915329980.

The previous prime is 15915329953. The next prime is 15915330043. The reversal of 15915329981 is 18992351951.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15613752025 + 301577956 = 124955^2 + 17366^2 .

It is a cyclic number.

It is not a de Polignac number, because 15915329981 - 2²² = 15911135677 is a prime.

It is a super-2 number, since 2×15915329981² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15915329951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7957664990 + 7957664991.

It is an arithmetic number, because the mean of its divisors is an integer number (7957664991).

Almost surely, 2^15915329981 is an apocalyptic number.

It is an amenable number.

15915329981 is a deficient number, since it is larger than the sum of its proper divisors (1).

15915329981 is an equidigital number, since it uses as much as digits as its factorization.

15915329981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 874800, while the sum is 53.

The spelling of 15915329981 in words is "fifteen billion, nine hundred fifteen million, three hundred twenty-nine thousand, nine hundred eighty-one".