21508272 has 60 divisors (see below), whose sum is σ = 61678344. Its totient is φ = 6992640.

The previous prime is 21508271. The next prime is 21508297. The reversal of 21508272 is 27280512.

It is not an unprimeable number, because it can be changed into a prime (21508271) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4083 + ... + 7725.

Almost surely, 2^21508272 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21508272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30839172).

21508272 is an abundant number, since it is smaller than the sum of its proper divisors (40170072).

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

21508272 is a wasteful number, since it uses less digits than its factorization.

21508272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3698 (or 3689 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21508272 is about 4637.7011546670. The cubic root of 21508272 is about 278.1005450366.

Adding to 21508272 its reverse (27280512), we get a palindrome (48788784).

The spelling of 21508272 in words is "twenty-one million, five hundred eight thousand, two hundred seventy-two".