21021212112009 has 4 divisors (see below), whose sum is σ = 28028282816016. Its totient is φ = 14014141408004.

The previous prime is 21021212112001. The next prime is 21021212112011. The reversal of 21021212112009 is 90021121212012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21021212112009 - 2³ = 21021212112001 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21021212112009.

It is not an unprimeable number, because it can be changed into a prime (21021212112001) 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, 3503535351999 + ... + 3503535352004.

It is an arithmetic number, because the mean of its divisors is an integer number (7007070704004).

Almost surely, 2^{21021212112009} is an apocalyptic number.

It is an amenable number.

21021212112009 is a deficient number, since it is larger than the sum of its proper divisors (7007070704007).

21021212112009 is an equidigital number, since it uses as much as digits as its factorization.

21021212112009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7007070704006.

The product of its (nonzero) digits is 288, while the sum is 24.

The spelling of 21021212112009 in words is "twenty-one trillion, twenty-one billion, two hundred twelve million, one hundred twelve thousand, nine".