21245172 has 48 divisors (see below), whose sum is σ = 56532672. Its totient is φ = 6151680.

The previous prime is 21245167. The next prime is 21245179. The reversal of 21245172 is 27154212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1354 + ... + 6657.

It is an arithmetic number, because the mean of its divisors is an integer number (1177764).

Almost surely, 2^21245172 is an apocalyptic number.

It is an amenable number.

21245172 is an abundant number, since it is smaller than the sum of its proper divisors (35287500).

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

21245172 is a wasteful number, since it uses less digits than its factorization.

21245172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8048 (or 8046 counting only the distinct ones).

The product of its digits is 1120, while the sum is 24.

The square root of 21245172 is about 4609.2485287734. The cubic root of 21245172 is about 276.9619344096.

Adding to 21245172 its reverse (27154212), we get a palindrome (48399384).

The spelling of 21245172 in words is "twenty-one million, two hundred forty-five thousand, one hundred seventy-two".