18663813 has 12 divisors (see below), whose sum is σ = 30810208. Its totient is φ = 10665000.

The previous prime is 18663811. The next prime is 18663817. The reversal of 18663813 is 31836681.

18663813 is a `hidden beast` number, since 1 + 8 + 6 + 638 + 13 = 666.

It is not a de Polignac number, because 18663813 - 2¹ = 18663811 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 (18663811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 148063 + ... + 148188.

Almost surely, 2^18663813 is an apocalyptic number.

It is an amenable number.

18663813 is a deficient number, since it is larger than the sum of its proper divisors (12146395).

18663813 is a wasteful number, since it uses less digits than its factorization.

18663813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296264 (or 296261 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 18663813 is about 4320.1635385712. The cubic root of 18663813 is about 265.2569620960.

The spelling of 18663813 in words is "eighteen million, six hundred sixty-three thousand, eight hundred thirteen".