21188212 has 12 divisors (see below), whose sum is σ = 38358180. Its totient is φ = 10228736.

The previous prime is 21188197. The next prime is 21188213. The reversal of 21188212 is 21288112.

It can be written as a sum of positive squares in 2 ways, for example, as 12916836 + 8271376 = 3594^2 + 2876^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21188213) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 91213 + ... + 91444.

It is an arithmetic number, because the mean of its divisors is an integer number (3196515).

Almost surely, 2^21188212 is an apocalyptic number.

It is an amenable number.

21188212 is a deficient number, since it is larger than the sum of its proper divisors (17169968).

21188212 is a wasteful number, since it uses less digits than its factorization.

21188212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182690 (or 182688 counting only the distinct ones).

The product of its digits is 512, while the sum is 25.

The square root of 21188212 is about 4603.0655002943. The cubic root of 21188212 is about 276.7141938641.

The spelling of 21188212 in words is "twenty-one million, one hundred eighty-eight thousand, two hundred twelve".