16399987 has 2 divisors, whose sum is σ = 16399988. Its totient is φ = 16399986.

The previous prime is 16399979. The next prime is 16400017. The reversal of 16399987 is 78999361.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 16399987 - 2³ = 16399979 is a prime.

It is not a weakly prime, because it can be changed into another prime (16399937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8199993 + 8199994.

It is an arithmetic number, because the mean of its divisors is an integer number (8199994).

Almost surely, 2^16399987 is an apocalyptic number.

16399987 is a deficient number, since it is larger than the sum of its proper divisors (1).

16399987 is an equidigital number, since it uses as much as digits as its factorization.

16399987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 734832, while the sum is 52.

The square root of 16399987 is about 4049.6897412024. The cubic root of 16399987 is about 254.0667514230.

The spelling of 16399987 in words is "sixteen million, three hundred ninety-nine thousand, nine hundred eighty-seven".