18990813 has 8 divisors (see below), whose sum is σ = 25347168. Its totient is φ = 12647504.

The previous prime is 18990809. The next prime is 18990827. The reversal of 18990813 is 31809981.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18990813 - 2² = 18990809 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18990833) 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 7 ways as a sum of consecutive naturals, for example, 895 + ... + 6227.

It is an arithmetic number, because the mean of its divisors is an integer number (3168396).

Almost surely, 2^18990813 is an apocalyptic number.

It is an amenable number.

18990813 is a deficient number, since it is larger than the sum of its proper divisors (6356355).

18990813 is a wasteful number, since it uses less digits than its factorization.

18990813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6523.

The product of its (nonzero) digits is 15552, while the sum is 39.

The square root of 18990813 is about 4357.8449949488. The cubic root of 18990813 is about 266.7971498579.

The spelling of 18990813 in words is "eighteen million, nine hundred ninety thousand, eight hundred thirteen".