21545772 has 48 divisors (see below), whose sum is σ = 53948160. Its totient is φ = 6671808.

The previous prime is 21545759. The next prime is 21545773. The reversal of 21545772 is 27754512.

It is not an unprimeable number, because it can be changed into a prime (21545773) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11193 + ... + 12975.

It is an arithmetic number, because the mean of its divisors is an integer number (1123920).

Almost surely, 2^21545772 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 21545772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26974080).

21545772 is an abundant number, since it is smaller than the sum of its proper divisors (32402388).

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

21545772 is a wasteful number, since it uses less digits than its factorization.

21545772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1862 (or 1860 counting only the distinct ones).

The product of its digits is 19600, while the sum is 33.

The square root of 21545772 is about 4641.7423452837. The cubic root of 21545772 is about 278.2620753755.

The spelling of 21545772 in words is "twenty-one million, five hundred forty-five thousand, seven hundred seventy-two".