18870813 has 20 divisors (see below), whose sum is σ = 30359868. Its totient is φ = 11612160.

The previous prime is 18870811. The next prime is 18870821. The reversal of 18870813 is 31807881.

It can be written as a sum of positive squares in 2 ways, for example, as 1205604 + 17665209 = 1098^2 + 4203^2 .

It is not a de Polignac number, because 18870813 - 2¹ = 18870811 is a prime.

It is a super-2 number, since 2×18870813² = 712215166561938, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18870811) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 7908 + ... + 10013.

Almost surely, 2^18870813 is an apocalyptic number.

18870813 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

18870813 is a deficient number, since it is larger than the sum of its proper divisors (11489055).

18870813 is a wasteful number, since it uses less digits than its factorization.

18870813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17946 (or 17937 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 18870813 is about 4344.0549029680. The cubic root of 18870813 is about 266.2340121326.

It can be divided in two parts, 18870 and 813, that added together give a 9-th power (19683 = 3⁹).

The spelling of 18870813 in words is "eighteen million, eight hundred seventy thousand, eight hundred thirteen".