21666722 has 48 divisors (see below), whose sum is σ = 41860800. Its totient is φ = 8316000.

The previous prime is 21666709. The next prime is 21666731. The reversal of 21666722 is 22766612.

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 108779 + ... + 108977.

It is an arithmetic number, because the mean of its divisors is an integer number (872100).

Almost surely, 2^21666722 is an apocalyptic number.

21666722 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21666722 is a deficient number, since it is larger than the sum of its proper divisors (20194078).

21666722 is a wasteful number, since it uses less digits than its factorization.

21666722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327 (or 320 counting only the distinct ones).

The product of its digits is 12096, while the sum is 32.

The square root of 21666722 is about 4654.7526250060. The cubic root of 21666722 is about 278.7817909005.

It can be divided in two parts, 216667 and 22, that multiplied together give a palindrome (4766674).

The spelling of 21666722 in words is "twenty-one million, six hundred sixty-six thousand, seven hundred twenty-two".