21513224 has 16 divisors (see below), whose sum is σ = 40387920. Its totient is φ = 10743120.

The previous prime is 21513209. The next prime is 21513227. The reversal of 21513224 is 42231512.

It is a junction number, because it is equal to n+sod(n) for n = 21513196 and 21513205.

It is not an unprimeable number, because it can be changed into a prime (21513227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9287 + ... + 11369.

It is an arithmetic number, because the mean of its divisors is an integer number (2524245).

Almost surely, 2^21513224 is an apocalyptic number.

It is an amenable number.

21513224 is a deficient number, since it is larger than the sum of its proper divisors (18874696).

21513224 is a wasteful number, since it uses less digits than its factorization.

21513224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3380 (or 3376 counting only the distinct ones).

The product of its digits is 480, while the sum is 20.

The square root of 21513224 is about 4638.2350091387. The cubic root of 21513224 is about 278.1218864105.

Adding to 21513224 its reverse (42231512), we get a palindrome (63744736).

The spelling of 21513224 in words is "twenty-one million, five hundred thirteen thousand, two hundred twenty-four".