21224456 has 64 divisors (see below), whose sum is σ = 45619200. Its totient is φ = 9172800.

The previous prime is 21224447. The next prime is 21224479. The reversal of 21224456 is 65442212.

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, 268625 + ... + 268703.

It is an arithmetic number, because the mean of its divisors is an integer number (712800).

Almost surely, 2^21224456 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 21224456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22809600).

21224456 is an abundant number, since it is smaller than the sum of its proper divisors (24394744).

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

21224456 is a wasteful number, since it uses less digits than its factorization.

21224456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210 (or 206 counting only the distinct ones).

The product of its digits is 3840, while the sum is 26.

The square root of 21224456 is about 4607.0007597134. Note that the first 3 decimals coincide. The cubic root of 21224456 is about 276.8718840000.

Adding to 21224456 its reverse (65442212), we get a palindrome (86666668).

The spelling of 21224456 in words is "twenty-one million, two hundred twenty-four thousand, four hundred fifty-six".