21865472 has 44 divisors (see below), whose sum is σ = 44313456. Its totient is φ = 10782720.

The previous prime is 21865469. The next prime is 21865531. The reversal of 21865472 is 27456812.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134063 + ... + 134225.

It is an arithmetic number, because the mean of its divisors is an integer number (1007124).

Almost surely, 2^21865472 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 21865472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22156728).

21865472 is an abundant number, since it is smaller than the sum of its proper divisors (22447984).

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

21865472 is a wasteful number, since it uses less digits than its factorization.

21865472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314 (or 296 counting only the distinct ones).

The product of its digits is 26880, while the sum is 35.

The square root of 21865472 is about 4676.0530364828. The cubic root of 21865472 is about 279.6316244112.

The spelling of 21865472 in words is "twenty-one million, eight hundred sixty-five thousand, four hundred seventy-two".