21212012109 has 16 divisors (see below), whose sum is σ = 28977044544. Its totient is φ = 13794268800.

The previous prime is 21212012069. The next prime is 21212012141. The reversal of 21212012109 is 90121021212.

It is not a de Polignac number, because 21212012109 - 2²⁰ = 21210963533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212012149) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1262367 + ... + 1279059.

It is an arithmetic number, because the mean of its divisors is an integer number (1811065284).

Almost surely, 2^21212012109 is an apocalyptic number.

It is an amenable number.

21212012109 is a deficient number, since it is larger than the sum of its proper divisors (7765032435).

21212012109 is a wasteful number, since it uses less digits than its factorization.

21212012109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27068.

The product of its (nonzero) digits is 144, while the sum is 21.

The spelling of 21212012109 in words is "twenty-one billion, two hundred twelve million, twelve thousand, one hundred nine".