21731272 has 32 divisors (see below), whose sum is σ = 41990400. Its totient is φ = 10538944.

The previous prime is 21731263. The next prime is 21731273. The reversal of 21731272 is 27213712.

It is not an unprimeable number, because it can be changed into a prime (21731273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45129 + ... + 45607.

It is an arithmetic number, because the mean of its divisors is an integer number (1312200).

Almost surely, 2^21731272 is an apocalyptic number.

It is an amenable number.

21731272 is a deficient number, since it is larger than the sum of its proper divisors (20259128).

21731272 is a wasteful number, since it uses less digits than its factorization.

21731272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 645 (or 641 counting only the distinct ones).

The product of its digits is 1176, while the sum is 25.

The square root of 21731272 is about 4661.6812417839. The cubic root of 21731272 is about 279.0583674770.

Adding to 21731272 its reverse (27213712), we get a palindrome (48944984).

The spelling of 21731272 in words is "twenty-one million, seven hundred thirty-one thousand, two hundred seventy-two".