21938412 has 48 divisors (see below), whose sum is σ = 54012672. Its totient is φ = 6916800.

The previous prime is 21938401. The next prime is 21938417. The reversal of 21938412 is 21483912.

It is a self number, because there is not a number n which added to its sum of digits gives 21938412.

It is not an unprimeable number, because it can be changed into a prime (21938417) 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, 27483 + ... + 28269.

It is an arithmetic number, because the mean of its divisors is an integer number (1125264).

Almost surely, 2^21938412 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 21938412, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27006336).

21938412 is an abundant number, since it is smaller than the sum of its proper divisors (32074260).

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

21938412 is a wasteful number, since it uses less digits than its factorization.

21938412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 918 (or 916 counting only the distinct ones).

The product of its digits is 3456, while the sum is 30.

The square root of 21938412 is about 4683.8458557045. The cubic root of 21938412 is about 279.9422159670.

The spelling of 21938412 in words is "twenty-one million, nine hundred thirty-eight thousand, four hundred twelve".