813678021 has 64 divisors (see below), whose sum is σ = 1447084800. Its totient is φ = 446404608.

The previous prime is 813678017. The next prime is 813678023. The reversal of 813678021 is 120876318.

It is not a de Polignac number, because 813678021 - 2² = 813678017 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (813678023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 109785 + ... + 116961.

It is an arithmetic number, because the mean of its divisors is an integer number (22610700).

Almost surely, 2^813678021 is an apocalyptic number.

It is an amenable number.

813678021 is a deficient number, since it is larger than the sum of its proper divisors (633406779).

813678021 is a wasteful number, since it uses less digits than its factorization.

813678021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7235 (or 7229 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 813678021 is about 28525.0419982162. The cubic root of 813678021 is about 933.5785433805.

The spelling of 813678021 in words is "eight hundred thirteen million, six hundred seventy-eight thousand, twenty-one".