21705572 has 24 divisors (see below), whose sum is σ = 44909760. Its totient is φ = 8981280.

The previous prime is 21705571. The next prime is 21705577. The reversal of 21705572 is 27550712.

It is a super-2 number, since 2×21705572² = 942263711694368, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21705571) 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, 12554 + ... + 14177.

It is an arithmetic number, because the mean of its divisors is an integer number (1871240).

Almost surely, 2^21705572 is an apocalyptic number.

It is an amenable number.

21705572 is an abundant number, since it is smaller than the sum of its proper divisors (23204188).

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

21705572 is a wasteful number, since it uses less digits than its factorization.

21705572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26771 (or 26769 counting only the distinct ones).

The product of its (nonzero) digits is 4900, while the sum is 29.

The square root of 21705572 is about 4658.9239100891. The cubic root of 21705572 is about 278.9483167156.

The spelling of 21705572 in words is "twenty-one million, seven hundred five thousand, five hundred seventy-two".