63818991 has 12 divisors (see below), whose sum is σ = 92252368. Its totient is φ = 42513984.

The previous prime is 63818981. The next prime is 63818999. The reversal of 63818991 is 19981836.

63818991 is a `hidden beast` number, since 638 + 1 + 8 + 9 + 9 + 1 = 666.

It is not a de Polignac number, because 63818991 - 2⁵ = 63818959 is a prime.

It is a super-2 number, since 2×63818991² = 8145727224516162, 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 (63818999) 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, 21111 + ... + 23943.

Almost surely, 2^63818991 is an apocalyptic number.

63818991 is a deficient number, since it is larger than the sum of its proper divisors (28433377).

63818991 is a wasteful number, since it uses less digits than its factorization.

63818991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5342 (or 5339 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 63818991 is about 7988.6789270817. The cubic root of 63818991 is about 399.6225418421.

The spelling of 63818991 in words is "sixty-three million, eight hundred eighteen thousand, nine hundred ninety-one".