21864224 has 12 divisors (see below), whose sum is σ = 43045254. Its totient is φ = 10932096.

The previous prime is 21864217. The next prime is 21864229. The reversal of 21864224 is 42246812.

It can be written as a sum of positive squares in only one way, i.e., 13454224 + 8410000 = 3668^2 + 2900^2 .

It is a super-2 number, since 2×21864224² = 956088582244352, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21864229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 341597 + ... + 341660.

Almost surely, 2^21864224 is an apocalyptic number.

It is an amenable number.

21864224 is a deficient number, since it is larger than the sum of its proper divisors (21181030).

21864224 is an equidigital number, since it uses as much as digits as its factorization.

21864224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 683267 (or 683259 counting only the distinct ones).

The product of its digits is 6144, while the sum is 29.

The square root of 21864224 is about 4675.9195887012. The cubic root of 21864224 is about 279.6263041981.

The spelling of 21864224 in words is "twenty-one million, eight hundred sixty-four thousand, two hundred twenty-four".