21252480 has 64 divisors (see below), whose sum is σ = 67748400. Its totient is φ = 5666816.

The previous prime is 21252457. The next prime is 21252487. The reversal of 21252480 is 8425212.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21252480.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252487) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3615 + ... + 7454.

Almost surely, 2^21252480 is an apocalyptic number.

21252480 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21252480 is an abundant number, since it is smaller than the sum of its proper divisors (46495920).

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

21252480 is a wasteful number, since it uses less digits than its factorization.

21252480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11091 (or 11079 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21252480 is about 4610.0412145663. The cubic root of 21252480 is about 276.9936875970.

Adding to 21252480 its reverse (8425212), we get a palindrome (29677692).

The spelling of 21252480 in words is "twenty-one million, two hundred fifty-two thousand, four hundred eighty".