21722736 has 80 divisors (see below), whose sum is σ = 67924224. Its totient is φ = 5839872.

The previous prime is 21722717. The next prime is 21722747. The reversal of 21722736 is 63722712.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 3811 + ... + 7613.

Almost surely, 2^21722736 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 21722736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33962112).

21722736 is an abundant number, since it is smaller than the sum of its proper divisors (46201488).

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

21722736 is a wasteful number, since it uses less digits than its factorization.

21722736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3838 (or 3832 counting only the distinct ones).

The product of its digits is 7056, while the sum is 30.

The square root of 21722736 is about 4660.7656023447. The cubic root of 21722736 is about 279.0218248366.

The spelling of 21722736 in words is "twenty-one million, seven hundred twenty-two thousand, seven hundred thirty-six".