18212813 has 4 divisors (see below), whose sum is σ = 18225180. Its totient is φ = 18200448.

The previous prime is 18212807. The next prime is 18212827. The reversal of 18212813 is 31821281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31821281 = 4657 ⋅6833.

It can be written as a sum of positive squares in 2 ways, for example, as 2036329 + 16176484 = 1427^2 + 4022^2 .

It is a cyclic number.

It is not a de Polignac number, because 18212813 - 2⁶ = 18212749 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 (18212833) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3620 + ... + 7037.

It is an arithmetic number, because the mean of its divisors is an integer number (4556295).

Almost surely, 2^18212813 is an apocalyptic number.

It is an amenable number.

18212813 is a deficient number, since it is larger than the sum of its proper divisors (12367).

18212813 is a wasteful number, since it uses less digits than its factorization.

18212813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12366.

The product of its digits is 768, while the sum is 26.

The square root of 18212813 is about 4267.6472440913. The cubic root of 18212813 is about 263.1029249163.

The spelling of 18212813 in words is "eighteen million, two hundred twelve thousand, eight hundred thirteen".