21183813 has 12 divisors (see below), whose sum is σ = 34970208. Its totient is φ = 12105000.

The previous prime is 21183809. The next prime is 21183829. The reversal of 21183813 is 31838112.

It is not a de Polignac number, because 21183813 - 2² = 21183809 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21183863) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 168063 + ... + 168188.

It is an arithmetic number, because the mean of its divisors is an integer number (2914184).

Almost surely, 2^21183813 is an apocalyptic number.

It is an amenable number.

21183813 is a deficient number, since it is larger than the sum of its proper divisors (13786395).

21183813 is a wasteful number, since it uses less digits than its factorization.

21183813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336264 (or 336261 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 21183813 is about 4602.5876417511. The cubic root of 21183813 is about 276.6950424921.

The spelling of 21183813 in words is "twenty-one million, one hundred eighty-three thousand, eight hundred thirteen".