21221272 has 64 divisors (see below), whose sum is σ = 44452800. Its totient is φ = 9461760.

The previous prime is 21221257. The next prime is 21221273. The reversal of 21221272 is 27212212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221273) 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 15 ways as a sum of consecutive naturals, for example, 218728 + ... + 218824.

It is an arithmetic number, because the mean of its divisors is an integer number (694575).

Almost surely, 2^21221272 is an apocalyptic number.

It is an amenable number.

21221272 is an abundant number, since it is smaller than the sum of its proper divisors (23231528).

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

21221272 is a wasteful number, since it uses less digits than its factorization.

21221272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196 (or 192 counting only the distinct ones).

The product of its digits is 224, while the sum is 19.

The square root of 21221272 is about 4606.6551857069. The cubic root of 21221272 is about 276.8580382715.

Adding to 21221272 its reverse (27212212), we get a palindrome (48433484).

The spelling of 21221272 in words is "twenty-one million, two hundred twenty-one thousand, two hundred seventy-two".