816881687 has 4 divisors (see below), whose sum is σ = 859875480. Its totient is φ = 773887896.

The previous prime is 816881641. The next prime is 816881693. The reversal of 816881687 is 786188618.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 816881687 - 2⁸ = 816881431 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816881617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21496868 + ... + 21496905.

It is an arithmetic number, because the mean of its divisors is an integer number (214968870).

Almost surely, 2^816881687 is an apocalyptic number.

816881687 is a deficient number, since it is larger than the sum of its proper divisors (42993793).

816881687 is a wasteful number, since it uses less digits than its factorization.

816881687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42993792.

The product of its digits is 1032192, while the sum is 53.

The square root of 816881687 is about 28581.1421570237. The cubic root of 816881687 is about 934.8021875561.

The spelling of 816881687 in words is "eight hundred sixteen million, eight hundred eighty-one thousand, six hundred eighty-seven".