21224288 has 24 divisors (see below), whose sum is σ = 43228080. Its totient is φ = 10245760.

The previous prime is 21224267. The next prime is 21224293. The reversal of 21224288 is 88242212.

It is a super-2 number, since 2×21224288² = 900940802213888, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21224288.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10508 + ... + 12363.

It is an arithmetic number, because the mean of its divisors is an integer number (1801170).

Almost surely, 2^21224288 is an apocalyptic number.

It is an amenable number.

21224288 is an abundant number, since it is smaller than the sum of its proper divisors (22003792).

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

21224288 is a wasteful number, since it uses less digits than its factorization.

21224288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22910 (or 22902 counting only the distinct ones).

The product of its digits is 4096, while the sum is 29.

The square root of 21224288 is about 4606.9825265568. The cubic root of 21224288 is about 276.8711534811.

It can be divided in two parts, 21224 and 288, that added together give a palindrome (21512).

The spelling of 21224288 in words is "twenty-one million, two hundred twenty-four thousand, two hundred eighty-eight".