21210012 has 36 divisors (see below), whose sum is σ = 55602456. Its totient is φ = 7069680.

The previous prime is 21210011. The next prime is 21210037. The reversal of 21210012 is 21001212.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21209976 and 21210003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210011) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9939 + ... + 11882.

Almost surely, 2^21210012 is an apocalyptic number.

It is an amenable number.

21210012 is an abundant number, since it is smaller than the sum of its proper divisors (34392444).

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

21210012 is a wasteful number, since it uses less digits than its factorization.

21210012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21840 (or 21826 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21210012 is about 4605.4328786771. The cubic root of 21210012 is about 276.8090626801.

Adding to 21210012 its reverse (21001212), we get a palindrome (42211224).

The spelling of 21210012 in words is "twenty-one million, two hundred ten thousand, twelve".