21986866 has 16 divisors (see below), whose sum is σ = 36415008. Its totient is φ = 9872800.

The previous prime is 21986863. The next prime is 21986879. The reversal of 21986866 is 66868912.

It is not an unprimeable number, because it can be changed into a prime (21986863) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4195 + ... + 7846.

It is an arithmetic number, because the mean of its divisors is an integer number (2275938).

Almost surely, 2^21986866 is an apocalyptic number.

21986866 is a deficient number, since it is larger than the sum of its proper divisors (14428142).

21986866 is a wasteful number, since it uses less digits than its factorization.

21986866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12137.

The product of its digits is 248832, while the sum is 46.

The square root of 21986866 is about 4689.0154616934. The cubic root of 21986866 is about 280.1481613828.

The spelling of 21986866 in words is "twenty-one million, nine hundred eighty-six thousand, eight hundred sixty-six".