21225456 has 80 divisors (see below), whose sum is σ = 69638400. Its totient is φ = 6063552.

The previous prime is 21225437. The next prime is 21225473. The reversal of 21225456 is 65452212.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 486 + ... + 6533.

It is an arithmetic number, because the mean of its divisors is an integer number (870480).

Almost surely, 2^21225456 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 21225456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34819200).

21225456 is an abundant number, since it is smaller than the sum of its proper divisors (48412944).

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

21225456 is a wasteful number, since it uses less digits than its factorization.

21225456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7043 (or 7031 counting only the distinct ones).

The product of its digits is 4800, while the sum is 27.

The square root of 21225456 is about 4607.1092889143. The cubic root of 21225456 is about 276.8762322471.

Adding to 21225456 its reverse (65452212), we get a palindrome (86677668).

The spelling of 21225456 in words is "twenty-one million, two hundred twenty-five thousand, four hundred fifty-six".