21813418 has 16 divisors (see below), whose sum is σ = 35774784. Its totient is φ = 9892960.

The previous prime is 21813403. The next prime is 21813419. The reversal of 21813418 is 81431812.

It is not an unprimeable number, because it can be changed into a prime (21813419) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12771 + ... + 14377.

It is an arithmetic number, because the mean of its divisors is an integer number (2235924).

Almost surely, 2^21813418 is an apocalyptic number.

21813418 is a deficient number, since it is larger than the sum of its proper divisors (13961366).

21813418 is a wasteful number, since it uses less digits than its factorization.

21813418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2237.

The product of its digits is 1536, while the sum is 28.

The square root of 21813418 is about 4670.4837008601. The cubic root of 21813418 is about 279.4095465656.

The spelling of 21813418 in words is "twenty-one million, eight hundred thirteen thousand, four hundred eighteen".