21940218 has 12 divisors (see below), whose sum is σ = 47537178. Its totient is φ = 7313400.

The previous prime is 21940201. The next prime is 21940241. The reversal of 21940218 is 81204912.

It can be written as a sum of positive squares in only one way, i.e., 19421649 + 2518569 = 4407^2 + 1587^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21940191 and 21940200.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 609433 + ... + 609468.

Almost surely, 2^21940218 is an apocalyptic number.

21940218 is an abundant number, since it is smaller than the sum of its proper divisors (25596960).

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

21940218 is a wasteful number, since it uses less digits than its factorization.

21940218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1218909 (or 1218906 counting only the distinct ones).

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

The square root of 21940218 is about 4684.0386420268. The cubic root of 21940218 is about 279.9498974979.

The spelling of 21940218 in words is "twenty-one million, nine hundred forty thousand, two hundred eighteen".