21679218 has 32 divisors (see below), whose sum is σ = 52557120. Its totient is φ = 6569280.

The previous prime is 21679193. The next prime is 21679219. The reversal of 21679218 is 81297612.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21679219) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17655 + ... + 18842.

It is an arithmetic number, because the mean of its divisors is an integer number (1642410).

Almost surely, 2^21679218 is an apocalyptic number.

21679218 is an abundant number, since it is smaller than the sum of its proper divisors (30877902).

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

21679218 is a wasteful number, since it uses less digits than its factorization.

21679218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36519 (or 36513 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21679218 is about 4656.0947155315. The cubic root of 21679218 is about 278.8353751907.

The spelling of 21679218 in words is "twenty-one million, six hundred seventy-nine thousand, two hundred eighteen".