813435991 has 4 divisors (see below), whose sum is σ = 814671000. Its totient is φ = 812200984.

The previous prime is 813435989. The next prime is 813436033. The reversal of 813435991 is 199534318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199534318 = 2 ⋅99767159.

It is a cyclic number.

It is not a de Polignac number, because 813435991 - 2¹ = 813435989 is a prime.

It is a super-2 number, since 2×813435991² = 1323356222908304162, 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 (813435911) 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, 616516 + ... + 617833.

It is an arithmetic number, because the mean of its divisors is an integer number (203667750).

Almost surely, 2^813435991 is an apocalyptic number.

813435991 is a deficient number, since it is larger than the sum of its proper divisors (1235009).

813435991 is a wasteful number, since it uses less digits than its factorization.

813435991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1235008.

The product of its digits is 116640, while the sum is 43.

The square root of 813435991 is about 28520.7992700064. The cubic root of 813435991 is about 933.4859693253.

The spelling of 813435991 in words is "eight hundred thirteen million, four hundred thirty-five thousand, nine hundred ninety-one".