21845572 has 36 divisors (see below), whose sum is σ = 44758224. Its totient is φ = 9302160.

The previous prime is 21845563. The next prime is 21845597. The reversal of 21845572 is 27554812.

It is a happy number.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 44247 + ... + 44737.

It is an arithmetic number, because the mean of its divisors is an integer number (1243284).

Almost surely, 2^21845572 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 21845572, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22379112).

21845572 is an abundant number, since it is smaller than the sum of its proper divisors (22912652).

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

21845572 is a wasteful number, since it uses less digits than its factorization.

21845572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 736 (or 727 counting only the distinct ones).

The product of its digits is 22400, while the sum is 34.

The square root of 21845572 is about 4673.9246891665. The cubic root of 21845572 is about 279.5467667516.

The spelling of 21845572 in words is "twenty-one million, eight hundred forty-five thousand, five hundred seventy-two".