21768866 has 16 divisors (see below), whose sum is σ = 37739520. Its totient is φ = 9224160.

The previous prime is 21768853. The next prime is 21768883. The reversal of 21768866 is 66886712.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7490 + ... + 9981.

It is an arithmetic number, because the mean of its divisors is an integer number (2358720).

Almost surely, 2^21768866 is an apocalyptic number.

21768866 is a deficient number, since it is larger than the sum of its proper divisors (15970654).

21768866 is a wasteful number, since it uses less digits than its factorization.

21768866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17569.

The product of its digits is 193536, while the sum is 44.

The square root of 21768866 is about 4665.7117356305. The cubic root of 21768866 is about 279.2191937199.

The spelling of 21768866 in words is "twenty-one million, seven hundred sixty-eight thousand, eight hundred sixty-six".