21918866 has 8 divisors (see below), whose sum is σ = 33294720. Its totient is φ = 10820628.

The previous prime is 21918859. The next prime is 21918877. The reversal of 21918866 is 66881912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 69206 + ... + 69521.

It is an arithmetic number, because the mean of its divisors is an integer number (4161840).

Almost surely, 2^21918866 is an apocalyptic number.

21918866 is a deficient number, since it is larger than the sum of its proper divisors (11375854).

21918866 is a wasteful number, since it uses less digits than its factorization.

21918866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138808.

The product of its digits is 41472, while the sum is 41.

The square root of 21918866 is about 4681.7588575235. The cubic root of 21918866 is about 279.8590532116.

The spelling of 21918866 in words is "twenty-one million, nine hundred eighteen thousand, eight hundred sixty-six".