813804639 has 4 divisors (see below), whose sum is σ = 1085072856. Its totient is φ = 542536424.

The previous prime is 813804601. The next prime is 813804679. The reversal of 813804639 is 936408318.

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 813804639 - 2¹² = 813800543 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 813804639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (813804679) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135634104 + ... + 135634109.

It is an arithmetic number, because the mean of its divisors is an integer number (271268214).

Almost surely, 2^813804639 is an apocalyptic number.

813804639 is a deficient number, since it is larger than the sum of its proper divisors (271268217).

813804639 is a wasteful number, since it uses less digits than its factorization.

813804639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271268216.

The product of its (nonzero) digits is 124416, while the sum is 42.

The square root of 813804639 is about 28527.2613301733. The cubic root of 813804639 is about 933.6269661857.

The spelling of 813804639 in words is "eight hundred thirteen million, eight hundred four thousand, six hundred thirty-nine".