21573792 has 72 divisors (see below), whose sum is σ = 61847604. Its totient is φ = 7133184.

The previous prime is 21573791. The next prime is 21573803. The reversal of 21573792 is 29737512.

It can be written as a sum of positive squares in 2 ways, for example, as 21566736 + 7056 = 4644^2 + 84^2 .

It is a tau number, because it is divible by the number of its divisors (72).

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 (21573791) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 49608 + ... + 50040.

Almost surely, 2^21573792 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 21573792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30923802).

21573792 is an abundant number, since it is smaller than the sum of its proper divisors (40273812).

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

21573792 is a wasteful number, since it uses less digits than its factorization.

21573792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622 (or 611 counting only the distinct ones).

The product of its digits is 26460, while the sum is 36.

The square root of 21573792 is about 4644.7596277956. The cubic root of 21573792 is about 278.3826485420.

The spelling of 21573792 in words is "twenty-one million, five hundred seventy-three thousand, seven hundred ninety-two".