816812989 has 2 divisors, whose sum is σ = 816812990. Its totient is φ = 816812988.

The previous prime is 816812981. The next prime is 816813061. The reversal of 816812989 is 989218618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 768232089 + 48580900 = 27717^2 + 6970^2 .

It is a cyclic number.

It is not a de Polignac number, because 816812989 - 2³ = 816812981 is a prime.

It is a super-2 number, since 2×816812989² = 1334366917998228242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (816812981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408406494 + 408406495.

It is an arithmetic number, because the mean of its divisors is an integer number (408406495).

Almost surely, 2^816812989 is an apocalyptic number.

It is an amenable number.

816812989 is a deficient number, since it is larger than the sum of its proper divisors (1).

816812989 is an equidigital number, since it uses as much as digits as its factorization.

816812989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 497664, while the sum is 52.

The square root of 816812989 is about 28579.9403253401. The cubic root of 816812989 is about 934.7759818677.

The spelling of 816812989 in words is "eight hundred sixteen million, eight hundred twelve thousand, nine hundred eighty-nine".