21689956 has 24 divisors (see below), whose sum is σ = 39415040. Its totient is φ = 10432800.

The previous prime is 21689947. The next prime is 21689959. The reversal of 21689956 is 65998612.

It is not an unprimeable number, because it can be changed into a prime (21689959) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25750 + ... + 26578.

Almost surely, 2^21689956 is an apocalyptic number.

It is an amenable number.

21689956 is a deficient number, since it is larger than the sum of its proper divisors (17725084).

21689956 is a wasteful number, since it uses less digits than its factorization.

21689956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075 (or 1073 counting only the distinct ones).

The product of its digits is 233280, while the sum is 46.

The square root of 21689956 is about 4657.2476850604. The cubic root of 21689956 is about 278.8814045270.

The spelling of 21689956 in words is "twenty-one million, six hundred eighty-nine thousand, nine hundred fifty-six".