15953981 has 2 divisors, whose sum is σ = 15953982. Its totient is φ = 15953980.

The previous prime is 15953963. The next prime is 15953983. The reversal of 15953981 is 18935951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15531481 + 422500 = 3941^2 + 650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15953981 is a prime.

It is a super-2 number, since 2×15953981² = 509059019496722, which contains 22 as substring.

Together with 15953983, 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 (15953983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7976990 + 7976991.

It is an arithmetic number, because the mean of its divisors is an integer number (7976991).

Almost surely, 2^15953981 is an apocalyptic number.

It is an amenable number.

15953981 is a deficient number, since it is larger than the sum of its proper divisors (1).

15953981 is an equidigital number, since it uses as much as digits as its factorization.

15953981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48600, while the sum is 41.

The square root of 15953981 is about 3994.2434828137. The cubic root of 15953981 is about 251.7423933823.

The spelling of 15953981 in words is "fifteen million, nine hundred fifty-three thousand, nine hundred eighty-one".