15311981 has 2 divisors, whose sum is σ = 15311982. Its totient is φ = 15311980.

The previous prime is 15311977. The next prime is 15311987. The reversal of 15311981 is 18911351.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14945956 + 366025 = 3866^2 + 605^2 .

It is a cyclic number.

It is not a de Polignac number, because 15311981 - 2² = 15311977 is a prime.

It is a super-2 number, since 2×15311981² = 468913524288722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15311987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7655990 + 7655991.

It is an arithmetic number, because the mean of its divisors is an integer number (7655991).

Almost surely, 2^15311981 is an apocalyptic number.

It is an amenable number.

15311981 is a deficient number, since it is larger than the sum of its proper divisors (1).

15311981 is an equidigital number, since it uses as much as digits as its factorization.

15311981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 29.

The square root of 15311981 is about 3913.0526446753. The cubic root of 15311981 is about 248.3192915302.

The spelling of 15311981 in words is "fifteen million, three hundred eleven thousand, nine hundred eighty-one".