21125424 has 40 divisors (see below), whose sum is σ = 57786480. Its totient is φ = 6627328.

The previous prime is 21125393. The next prime is 21125443. The reversal of 21125424 is 42452112.

It is a self number, because there is not a number n which added to its sum of digits gives 21125424.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12129 + ... + 13760.

It is an arithmetic number, because the mean of its divisors is an integer number (1444662).

Almost surely, 2^21125424 is an apocalyptic number.

21125424 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21125424 is an abundant number, since it is smaller than the sum of its proper divisors (36661056).

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

21125424 is a wasteful number, since it uses less digits than its factorization.

21125424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25917 (or 25911 counting only the distinct ones).

The product of its digits is 640, while the sum is 21.

The square root of 21125424 is about 4596.2402026004. The cubic root of 21125424 is about 276.4405901394.

Adding to 21125424 its reverse (42452112), we get a palindrome (63577536).

The spelling of 21125424 in words is "twenty-one million, one hundred twenty-five thousand, four hundred twenty-four".