21111272 has 64 divisors (see below), whose sum is σ = 49835520. Its totient is φ = 8160768.

The previous prime is 21111257. The next prime is 21111283. The reversal of 21111272 is 27211112.

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21111272.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33908 + ... + 34524.

It is an arithmetic number, because the mean of its divisors is an integer number (778680).

Almost surely, 2^21111272 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21111272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24917760).

21111272 is an abundant number, since it is smaller than the sum of its proper divisors (28724248).

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

21111272 is a wasteful number, since it uses less digits than its factorization.

21111272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 690 (or 686 counting only the distinct ones).

The product of its digits is 56, while the sum is 17.

The square root of 21111272 is about 4594.7004254902. The cubic root of 21111272 is about 276.3788468240.

Adding to 21111272 its reverse (27211112), we get a palindrome (48322384).

The spelling of 21111272 in words is "twenty-one million, one hundred eleven thousand, two hundred seventy-two".