813157821 has 48 divisors (see below), whose sum is σ = 1454454144. Its totient is φ = 427133952.

The previous prime is 813157819. The next prime is 813157841. The reversal of 813157821 is 128751318.

813157821 is a `hidden beast` number, since 81 + 3 + 1 + 578 + 2 + 1 = 666.

It is not a de Polignac number, because 813157821 - 2¹ = 813157819 is a prime.

It is a super-2 number, since 2×813157821² = 1322451283706936082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (813157841) 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 47 ways as a sum of consecutive naturals, for example, 37225 + ... + 54881.

It is an arithmetic number, because the mean of its divisors is an integer number (30301128).

Almost surely, 2^813157821 is an apocalyptic number.

It is an amenable number.

813157821 is a deficient number, since it is larger than the sum of its proper divisors (641296323).

813157821 is a wasteful number, since it uses less digits than its factorization.

813157821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17730 (or 17727 counting only the distinct ones).

The product of its digits is 13440, while the sum is 36.

The square root of 813157821 is about 28515.9222365330. The cubic root of 813157821 is about 933.3795493980.

The spelling of 813157821 in words is "eight hundred thirteen million, one hundred fifty-seven thousand, eight hundred twenty-one".