21859218 has 12 divisors (see below), whose sum is σ = 47361678. Its totient is φ = 7286400.

The previous prime is 21859207. The next prime is 21859231. The reversal of 21859218 is 81295812.

It can be written as a sum of positive squares in only one way, i.e., 13373649 + 8485569 = 3657^2 + 2913^2 .

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, 607183 + ... + 607218.

Almost surely, 2^21859218 is an apocalyptic number.

21859218 is an abundant number, since it is smaller than the sum of its proper divisors (25502460).

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

21859218 is a wasteful number, since it uses less digits than its factorization.

21859218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1214409 (or 1214406 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 21859218 is about 4675.3842622826. The cubic root of 21859218 is about 279.6049616292.

The spelling of 21859218 in words is "twenty-one million, eight hundred fifty-nine thousand, two hundred eighteen".