816599891 has 2 divisors, whose sum is σ = 816599892. Its totient is φ = 816599890.

The previous prime is 816599887. The next prime is 816599921. The reversal of 816599891 is 198995618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 816599891 - 2² = 816599887 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (816599851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408299945 + 408299946.

It is an arithmetic number, because the mean of its divisors is an integer number (408299946).

Almost surely, 2^816599891 is an apocalyptic number.

816599891 is a deficient number, since it is larger than the sum of its proper divisors (1).

816599891 is an equidigital number, since it uses as much as digits as its factorization.

816599891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1399680, while the sum is 56.

The square root of 816599891 is about 28576.2119777972. The cubic root of 816599891 is about 934.6946836920.

The spelling of 816599891 in words is "eight hundred sixteen million, five hundred ninety-nine thousand, eight hundred ninety-one".