15131981 has 2 divisors, whose sum is σ = 15131982. Its totient is φ = 15131980.

The previous prime is 15131933. The next prime is 15131983. The reversal of 15131981 is 18913151.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14891881 + 240100 = 3859^2 + 490^2 .

It is a cyclic number.

It is not a de Polignac number, because 15131981 - 2⁶ = 15131917 is a prime.

It is a super-2 number, since 2×15131981² = 457953697968722, which contains 22 as substring.

Together with 15131983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15131983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7565990 + 7565991.

It is an arithmetic number, because the mean of its divisors is an integer number (7565991).

Almost surely, 2^15131981 is an apocalyptic number.

It is an amenable number.

15131981 is a deficient number, since it is larger than the sum of its proper divisors (1).

15131981 is an equidigital number, since it uses as much as digits as its factorization.

15131981 is an evil number, because the sum of its binary digits is even.

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

The square root of 15131981 is about 3889.9847043401. The cubic root of 15131981 is about 247.3424143944.

The spelling of 15131981 in words is "fifteen million, one hundred thirty-one thousand, nine hundred eighty-one".