21373218 has 24 divisors (see below), whose sum is σ = 47439756. Its totient is φ = 6950400.

The previous prime is 21373207. The next prime is 21373223. The reversal of 21373218 is 81237312.

It can be written as a sum of positive squares in 2 ways, for example, as 21372129 + 1089 = 4623^2 + 33^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21373191 and 21373200.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13743 + ... + 15218.

Almost surely, 2^21373218 is an apocalyptic number.

21373218 is an abundant number, since it is smaller than the sum of its proper divisors (26066538).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21373218 is a wasteful number, since it uses less digits than its factorization.

21373218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29010 (or 29007 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 21373218 is about 4623.1177791616. The cubic root of 21373218 is about 277.5172426588.

The spelling of 21373218 in words is "twenty-one million, three hundred seventy-three thousand, two hundred eighteen".