21505472 has 28 divisors (see below), whose sum is σ = 44150280. Its totient is φ = 10381056.

The previous prime is 21505469. The next prime is 21505481. The reversal of 21505472 is 27450512.

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, 3938 + ... + 7649.

Almost surely, 2^21505472 is an apocalyptic number.

It is an amenable number.

21505472 is an abundant number, since it is smaller than the sum of its proper divisors (22644808).

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

21505472 is a wasteful number, since it uses less digits than its factorization.

21505472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11628 (or 11618 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 21505472 is about 4637.3992711433. The cubic root of 21505472 is about 278.0884765741.

Adding to 21505472 its reverse (27450512), we get a palindrome (48955984).

The spelling of 21505472 in words is "twenty-one million, five hundred five thousand, four hundred seventy-two".