18436813 has 4 divisors (see below), whose sum is σ = 18560700. Its totient is φ = 18312928.

The previous prime is 18436811. The next prime is 18436819. The reversal of 18436813 is 31863481.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10125124 + 8311689 = 3182^2 + 2883^2 .

It is a cyclic number.

It is not a de Polignac number, because 18436813 - 2¹ = 18436811 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 (18436811) 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, 61720 + ... + 62017.

It is an arithmetic number, because the mean of its divisors is an integer number (4640175).

Almost surely, 2^18436813 is an apocalyptic number.

It is an amenable number.

18436813 is a deficient number, since it is larger than the sum of its proper divisors (123887).

18436813 is a wasteful number, since it uses less digits than its factorization.

18436813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123886.

The product of its digits is 13824, while the sum is 34.

The square root of 18436813 is about 4293.8110112114. The cubic root of 18436813 is about 264.1771700632.

The spelling of 18436813 in words is "eighteen million, four hundred thirty-six thousand, eight hundred thirteen".