21825440 has 96 divisors (see below), whose sum is σ = 63504000. Its totient is φ = 6902784.

The previous prime is 21825439. The next prime is 21825469. The reversal of 21825440 is 4452812.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13811 + ... + 15309.

It is an arithmetic number, because the mean of its divisors is an integer number (661500).

Almost surely, 2^21825440 is an apocalyptic number.

21825440 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 21825440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31752000).

21825440 is an abundant number, since it is smaller than the sum of its proper divisors (41678560).

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

21825440 is a wasteful number, since it uses less digits than its factorization.

21825440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1534 (or 1526 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 26.

The square root of 21825440 is about 4671.7705423105. The cubic root of 21825440 is about 279.4608673424.

The spelling of 21825440 in words is "twenty-one million, eight hundred twenty-five thousand, four hundred forty".