18688813 has 18 divisors (see below), whose sum is σ = 22327242. Its totient is φ = 15539040.

The previous prime is 18688801. The next prime is 18688819. The reversal of 18688813 is 31888681.

It can be written as a sum of positive squares in 3 ways, for example, as 2832489 + 15856324 = 1683^2 + 3982^2 .

It is not a de Polignac number, because 18688813 - 2¹³ = 18680621 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18688813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18688819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 171403 + ... + 171511.

Almost surely, 2^18688813 is an apocalyptic number.

18688813 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

18688813 is a deficient number, since it is larger than the sum of its proper divisors (3638429).

18688813 is a wasteful number, since it uses less digits than its factorization.

18688813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253 (or 133 counting only the distinct ones).

The product of its digits is 73728, while the sum is 43.

The square root of 18688813 is about 4323.0559792813. The cubic root of 18688813 is about 265.3753456464.

The spelling of 18688813 in words is "eighteen million, six hundred eighty-eight thousand, eight hundred thirteen".