813537999 has 12 divisors (see below), whose sum is σ = 1218633416. Its totient is φ = 542358504.

The previous prime is 813537979. The next prime is 813538001. The reversal of 813537999 is 999735318.

813537999 is a `hidden beast` number, since 8 + 13 + 537 + 9 + 99 = 666.

It is not a de Polignac number, because 813537999 - 2⁷ = 813537871 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (813537979) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1673704 + ... + 1674189.

Almost surely, 2^813537999 is an apocalyptic number.

813537999 is a deficient number, since it is larger than the sum of its proper divisors (405095417).

813537999 is an equidigital number, since it uses as much as digits as its factorization.

813537999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3347908 (or 3347896 counting only the distinct ones).

The product of its digits is 1837080, while the sum is 54.

The square root of 813537999 is about 28522.5875228739. The cubic root of 813537999 is about 933.5249886039.

The spelling of 813537999 in words is "eight hundred thirteen million, five hundred thirty-seven thousand, nine hundred ninety-nine".