21645792 has 120 divisors (see below), whose sum is σ = 72814896. Its totient is φ = 6179328.

The previous prime is 21645791. The next prime is 21645797. The reversal of 21645792 is 29754612.

21645792 is a `hidden beast` number, since 2 + 1 + 645 + 7 + 9 + 2 = 666.

It is a super-2 number, since 2×21645792² = 937080622614528, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21645791) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 17548 + ... + 18740.

Almost surely, 2^21645792 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 21645792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36407448).

21645792 is an abundant number, since it is smaller than the sum of its proper divisors (51169104).

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

21645792 is a wasteful number, since it uses less digits than its factorization.

21645792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1222 (or 1205 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 21645792 is about 4652.5038420188. The cubic root of 21645792 is about 278.6919944725.

The spelling of 21645792 in words is "twenty-one million, six hundred forty-five thousand, seven hundred ninety-two".