21212112309 has 16 divisors (see below), whose sum is σ = 28440035712. Its totient is φ = 14062868288.

The previous prime is 21212112209. The next prime is 21212112401. The reversal of 21212112309 is 90321121212.

It is a cyclic number.

It is not a de Polignac number, because 21212112309 - 2¹³ = 21212104117 is a prime.

It is a super-2 number, since 2×21212112309² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212112109) 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, 1424587 + ... + 1439399.

It is an arithmetic number, because the mean of its divisors is an integer number (1777502232).

Almost surely, 2^21212112309 is an apocalyptic number.

It is an amenable number.

21212112309 is a deficient number, since it is larger than the sum of its proper divisors (7227923403).

21212112309 is a wasteful number, since it uses less digits than its factorization.

21212112309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17436.

The product of its (nonzero) digits is 432, while the sum is 24.

The spelling of 21212112309 in words is "twenty-one billion, two hundred twelve million, one hundred twelve thousand, three hundred nine".