21918366 has 12 divisors (see below), whose sum is σ = 47489832. Its totient is φ = 7306116.

The previous prime is 21918361. The next prime is 21918367. The reversal of 21918366 is 66381912.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21918366.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21918361) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 608826 + ... + 608861.

It is an arithmetic number, because the mean of its divisors is an integer number (3957486).

Almost surely, 2^21918366 is an apocalyptic number.

21918366 is an abundant number, since it is smaller than the sum of its proper divisors (25571466).

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

21918366 is a wasteful number, since it uses less digits than its factorization.

21918366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1217695 (or 1217692 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 21918366 is about 4681.7054584841. The cubic root of 21918366 is about 279.8569252032.

The spelling of 21918366 in words is "twenty-one million, nine hundred eighteen thousand, three hundred sixty-six".