21534224 has 10 divisors (see below), whose sum is σ = 41722590. Its totient is φ = 10767104.

The previous prime is 21534221. The next prime is 21534241. The reversal of 21534224 is 42243512.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21529600 + 4624 = 4640^2 + 68^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21534224.

It is not an unprimeable number, because it can be changed into a prime (21534221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 672929 + ... + 672960.

It is an arithmetic number, because the mean of its divisors is an integer number (4172259).

Almost surely, 2^21534224 is an apocalyptic number.

It is an amenable number.

21534224 is a deficient number, since it is larger than the sum of its proper divisors (20188366).

21534224 is a wasteful number, since it uses less digits than its factorization.

21534224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1345897 (or 1345891 counting only the distinct ones).

The product of its digits is 1920, while the sum is 23.

The square root of 21534224 is about 4640.4982491108. The cubic root of 21534224 is about 278.2123526315.

Adding to 21534224 its reverse (42243512), we get a palindrome (63777736).

The spelling of 21534224 in words is "twenty-one million, five hundred thirty-four thousand, two hundred twenty-four".