21928400 has 60 divisors (see below), whose sum is σ = 56748972. Its totient is φ = 8094720.

The previous prime is 21928381. The next prime is 21928429. The reversal of 21928400 is 482912.

It can be written as a sum of positive squares in 6 ways, for example, as 287296 + 21641104 = 536^2 + 4652^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 21928400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3092 + ... + 7308.

Almost surely, 2^21928400 is an apocalyptic number.

21928400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21928400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28374486).

21928400 is an abundant number, since it is smaller than the sum of its proper divisors (34820572).

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

21928400 is a wasteful number, since it uses less digits than its factorization.

21928400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4248 (or 4237 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21928400 is about 4682.7769539025. The cubic root of 21928400 is about 279.8996238848.

The spelling of 21928400 in words is "twenty-one million, nine hundred twenty-eight thousand, four hundred".