21103272 has 48 divisors (see below), whose sum is σ = 57700500. Its totient is φ = 6967296.

The previous prime is 21103267. The next prime is 21103301. The reversal of 21103272 is 27230112.

It can be written as a sum of positive squares in 2 ways, for example, as 20304036 + 799236 = 4506^2 + 894^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6504 + ... + 9192.

Almost surely, 2^21103272 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 21103272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28850250).

21103272 is an abundant number, since it is smaller than the sum of its proper divisors (36597228).

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

21103272 is a wasteful number, since it uses less digits than its factorization.

21103272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2810 (or 2803 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21103272 is about 4593.8297748175. The cubic root of 21103272 is about 276.3439316672.

Adding to 21103272 its reverse (27230112), we get a palindrome (48333384).

The spelling of 21103272 in words is "twenty-one million, one hundred three thousand, two hundred seventy-two".