21105212 has 6 divisors (see below), whose sum is σ = 36934128. Its totient is φ = 10552604.

The previous prime is 21105199. The next prime is 21105221. The reversal of 21105212 is 21250112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2638148 + ... + 2638155.

It is an arithmetic number, because the mean of its divisors is an integer number (6155688).

Almost surely, 2^21105212 is an apocalyptic number.

It is an amenable number.

21105212 is a deficient number, since it is larger than the sum of its proper divisors (15828916).

21105212 is a wasteful number, since it uses less digits than its factorization.

21105212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5276307 (or 5276305 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21105212 is about 4594.0409227607. The cubic root of 21105212 is about 276.3523994030.

Adding to 21105212 its reverse (21250112), we get a palindrome (42355324).

The spelling of 21105212 in words is "twenty-one million, one hundred five thousand, two hundred twelve".