21103312 has 40 divisors (see below), whose sum is σ = 42632192. Its totient is φ = 10108800.

The previous prime is 21103309. The next prime is 21103321. The reversal of 21103312 is 21330112.

It is a junction number, because it is equal to n+sod(n) for n = 21103292 and 21103301.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 77737 + ... + 78007.

Almost surely, 2^21103312 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 21103312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21316096).

21103312 is an abundant number, since it is smaller than the sum of its proper divisors (21528880).

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

21103312 is a wasteful number, since it uses less digits than its factorization.

21103312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 467 (or 461 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21103312 is about 4593.8341284813. The cubic root of 21103312 is about 276.3441062649.

Adding to 21103312 its reverse (21330112), we get a palindrome (42433424).

The spelling of 21103312 in words is "twenty-one million, one hundred three thousand, three hundred twelve".