21102912 has 42 divisors (see below), whose sum is σ = 60489338. Its totient is φ = 7034112.

The previous prime is 21102911. The next prime is 21102919. The reversal of 21102912 is 21920112.

It can be written as a sum of positive squares in only one way, i.e., 16842816 + 4260096 = 4104^2 + 2064^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17743 + ... + 18894.

Almost surely, 2^21102912 is an apocalyptic number.

It is an amenable number.

21102912 is an abundant number, since it is smaller than the sum of its proper divisors (39386426).

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

21102912 is a wasteful number, since it uses less digits than its factorization.

21102912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36655 (or 36642 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21102912 is about 4593.7905916574. The cubic root of 21102912 is about 276.3423602776.

The spelling of 21102912 in words is "twenty-one million, one hundred two thousand, nine hundred twelve".