816868781 has 8 divisors (see below), whose sum is σ = 852792600. Its totient is φ = 781462080.

The previous prime is 816868739. The next prime is 816868783. The reversal of 816868781 is 187868618.

It is a happy number.

816868781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 62267881 + 754600900 = 7891^2 + 27470^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-816868781 is a prime.

It is a super-2 number, since 2×816868781² = 1334549210744851922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816868783) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 126050 + ... + 132371.

It is an arithmetic number, because the mean of its divisors is an integer number (106599075).

Almost surely, 2^816868781 is an apocalyptic number.

It is an amenable number.

816868781 is a deficient number, since it is larger than the sum of its proper divisors (35923819).

816868781 is a wasteful number, since it uses less digits than its factorization.

816868781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258559.

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

The square root of 816868781 is about 28580.9163778910. The cubic root of 816868781 is about 934.7972645174.

The spelling of 816868781 in words is "eight hundred sixteen million, eight hundred sixty-eight thousand, seven hundred eighty-one".