16391971 has 2 divisors, whose sum is σ = 16391972. Its totient is φ = 16391970.

The previous prime is 16391941. The next prime is 16392011. The reversal of 16391971 is 17919361.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16391971 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16391971.

It is not a weakly prime, because it can be changed into another prime (16391941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8195985 + 8195986.

It is an arithmetic number, because the mean of its divisors is an integer number (8195986).

Almost surely, 2^16391971 is an apocalyptic number.

16391971 is a deficient number, since it is larger than the sum of its proper divisors (1).

16391971 is an equidigital number, since it uses as much as digits as its factorization.

16391971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10206, while the sum is 37.

The square root of 16391971 is about 4048.6999147875. The cubic root of 16391971 is about 254.0253503539.

The spelling of 16391971 in words is "sixteen million, three hundred ninety-one thousand, nine hundred seventy-one".