21224449 has 9 divisors (see below), whose sum is σ = 22629891. Its totient is φ = 19902240.

The previous prime is 21224447. The next prime is 21224479. The reversal of 21224449 is 94442212.

The square root of 21224449 is 4607.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 16524225 + 4700224 = 4065^2 + 2168^2 .

It is not a de Polignac number, because 21224449 - 2¹ = 21224447 is a prime.

It is a Duffinian number.

Its product of digits (4608) is a multiple of the sum of its prime divisors (288).

It is not an unprimeable number, because it can be changed into a prime (21224447) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 78184 + ... + 78454.

Almost surely, 2^21224449 is an apocalyptic number.

21224449 is the 4607-th square number.

21224449 is the 2304-th centered octagonal number.

It is an amenable number.

21224449 is a deficient number, since it is larger than the sum of its proper divisors (1405442).

21224449 is an frugal number, since it uses more digits than its factorization.

21224449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 576 (or 288 counting only the distinct ones).

The product of its digits is 4608, while the sum is 28.

The cubic root of 21224449 is about 276.8718535618.

The spelling of 21224449 in words is "twenty-one million, two hundred twenty-four thousand, four hundred forty-nine".