21131472 has 20 divisors (see below), whose sum is σ = 54589760. Its totient is φ = 7043808.

The previous prime is 21131449. The next prime is 21131489. The reversal of 21131472 is 27413112.

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, 220072 + ... + 220167.

It is an arithmetic number, because the mean of its divisors is an integer number (2729488).

Almost surely, 2^21131472 is an apocalyptic number.

It is an amenable number.

21131472 is an abundant number, since it is smaller than the sum of its proper divisors (33458288).

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

21131472 is a wasteful number, since it uses less digits than its factorization.

21131472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 440250 (or 440244 counting only the distinct ones).

The product of its digits is 336, while the sum is 21.

The square root of 21131472 is about 4596.8980845783. The cubic root of 21131472 is about 276.4669683581.

Adding to 21131472 its reverse (27413112), we get a palindrome (48544584).

The spelling of 21131472 in words is "twenty-one million, one hundred thirty-one thousand, four hundred seventy-two".