21938472 has 64 divisors (see below), whose sum is σ = 62265600. Its totient is φ = 7153920.

The previous prime is 21938459. The next prime is 21938473. The reversal of 21938472 is 27483912.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

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 (21938473) 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, 9072 + ... + 11232.

It is an arithmetic number, because the mean of its divisors is an integer number (972900).

Almost surely, 2^21938472 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 21938472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31132800).

21938472 is an abundant number, since it is smaller than the sum of its proper divisors (40327128).

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

21938472 is a wasteful number, since it uses less digits than its factorization.

21938472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2223 (or 2213 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21938472 is about 4683.8522606931. The cubic root of 21938472 is about 279.9424711741.

The spelling of 21938472 in words is "twenty-one million, nine hundred thirty-eight thousand, four hundred seventy-two".