21186668 has 12 divisors (see below), whose sum is σ = 37981272. Its totient is φ = 10334880.

The previous prime is 21186637. The next prime is 21186677. The reversal of 21186668 is 86668112.

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, 64430 + ... + 64757.

It is an arithmetic number, because the mean of its divisors is an integer number (3165106).

Almost surely, 2^21186668 is an apocalyptic number.

It is an amenable number.

21186668 is a deficient number, since it is larger than the sum of its proper divisors (16794604).

21186668 is a wasteful number, since it uses less digits than its factorization.

21186668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129232 (or 129230 counting only the distinct ones).

The product of its digits is 27648, while the sum is 38.

The square root of 21186668 is about 4602.8977829189. The cubic root of 21186668 is about 276.7074722478.

The spelling of 21186668 in words is "twenty-one million, one hundred eighty-six thousand, six hundred sixty-eight".