21000212 has 24 divisors (see below), whose sum is σ = 37653504. Its totient is φ = 10245312.

The previous prime is 21000193. The next prime is 21000229. The reversal of 21000212 is 21200012.

It is a self number, because there is not a number n which added to its sum of digits gives 21000212.

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, 33728 + ... + 34344.

It is an arithmetic number, because the mean of its divisors is an integer number (1568896).

Almost surely, 2^21000212 is an apocalyptic number.

It is an amenable number.

21000212 is a deficient number, since it is larger than the sum of its proper divisors (16653292).

21000212 is a wasteful number, since it uses less digits than its factorization.

21000212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 815 (or 813 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 21000212 is about 4582.5988259938. The cubic root of 21000212 is about 275.8933460349.

Adding to 21000212 its reverse (21200012), we get a palindrome (42200224).

It can be divided in two parts, 21000 and 212, that added together give a palindrome (21212).

The spelling of 21000212 in words is "twenty-one million, two hundred twelve", and thus it is an aban number.