21666968 has 8 divisors (see below), whose sum is σ = 40625580. Its totient is φ = 10833480.

The previous prime is 21666949. The next prime is 21666971. The reversal of 21666968 is 86966612.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1354178 + ... + 1354193.

Almost surely, 2^21666968 is an apocalyptic number.

It is an amenable number.

21666968 is a deficient number, since it is larger than the sum of its proper divisors (18958612).

21666968 is a wasteful number, since it uses less digits than its factorization.

21666968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2708377 (or 2708373 counting only the distinct ones).

The product of its digits is 186624, while the sum is 44.

The square root of 21666968 is about 4654.7790495361. The cubic root of 21666968 is about 278.7828459757.

The spelling of 21666968 in words is "twenty-one million, six hundred sixty-six thousand, nine hundred sixty-eight".