21722688 has 112 divisors (see below), whose sum is σ = 68844160. Its totient is φ = 6676992.

The previous prime is 21722671. The next prime is 21722689. The reversal of 21722688 is 88622712.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21722689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21981 + ... + 22947.

It is an arithmetic number, because the mean of its divisors is an integer number (614680).

Almost surely, 2^21722688 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21722688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34422080).

21722688 is an abundant number, since it is smaller than the sum of its proper divisors (47121472).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21722688 is a wasteful number, since it uses less digits than its factorization.

21722688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1001 (or 985 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 21722688 is about 4660.7604529733. The cubic root of 21722688 is about 279.0216193214.

The spelling of 21722688 in words is "twenty-one million, seven hundred twenty-two thousand, six hundred eighty-eight".