21108312 has 48 divisors (see below), whose sum is σ = 58149000. Its totient is φ = 6915456.

The previous prime is 21108301. The next prime is 21108323. The reversal of 21108312 is 21380112.

It is an interprime number because it is at equal distance from previous prime (21108301) and next prime (21108323).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1764 + ... + 6732.

Almost surely, 2^21108312 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 21108312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29074500).

21108312 is an abundant number, since it is smaller than the sum of its proper divisors (37040688).

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

21108312 is a wasteful number, since it uses less digits than its factorization.

21108312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5040 (or 5033 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21108312 is about 4594.3783039711. The cubic root of 21108312 is about 276.3659292442.

Adding to 21108312 its reverse (21380112), we get a palindrome (42488424).

The spelling of 21108312 in words is "twenty-one million, one hundred eight thousand, three hundred twelve".