816919639 has 2 divisors, whose sum is σ = 816919640. Its totient is φ = 816919638.

The previous prime is 816919637. The next prime is 816919661. The reversal of 816919639 is 936919618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 816919639 - 2¹ = 816919637 is a prime.

Together with 816919637, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (816919637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408459819 + 408459820.

It is an arithmetic number, because the mean of its divisors is an integer number (408459820).

Almost surely, 2^816919639 is an apocalyptic number.

816919639 is a deficient number, since it is larger than the sum of its proper divisors (1).

816919639 is an equidigital number, since it uses as much as digits as its factorization.

816919639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 629856, while the sum is 52.

The square root of 816919639 is about 28581.8060835910. The cubic root of 816919639 is about 934.8166641785.

The spelling of 816919639 in words is "eight hundred sixteen million, nine hundred nineteen thousand, six hundred thirty-nine".