15987791 has 2 divisors, whose sum is σ = 15987792. Its totient is φ = 15987790.

The previous prime is 15987767. The next prime is 15987817. The reversal of 15987791 is 19778951.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 15987791 - 2²² = 11793487 is a prime.

It is a super-2 number, since 2×15987791² = 511218922119362, 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 (15987731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7993895 + 7993896.

It is an arithmetic number, because the mean of its divisors is an integer number (7993896).

Almost surely, 2^15987791 is an apocalyptic number.

15987791 is a deficient number, since it is larger than the sum of its proper divisors (1).

15987791 is an equidigital number, since it uses as much as digits as its factorization.

15987791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 158760, while the sum is 47.

The square root of 15987791 is about 3998.4735837567. The cubic root of 15987791 is about 251.9201004359.

The spelling of 15987791 in words is "fifteen million, nine hundred eighty-seven thousand, seven hundred ninety-one".