21212009999 has 8 divisors (see below), whose sum is σ = 21539374560. Its totient is φ = 20886624000.

The previous prime is 21212009993. The next prime is 21212010011. The reversal of 21212009999 is 99990021212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21212009999 - 2²⁰ = 21210961423 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212009993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 473027 + ... + 515924.

It is an arithmetic number, because the mean of its divisors is an integer number (2692421820).

Almost surely, 2^21212009999 is an apocalyptic number.

21212009999 is a deficient number, since it is larger than the sum of its proper divisors (327364561).

21212009999 is an equidigital number, since it uses as much as digits as its factorization.

21212009999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 989281.

The product of its (nonzero) digits is 52488, while the sum is 44.

The spelling of 21212009999 in words is "twenty-one billion, two hundred twelve million, nine thousand, nine hundred ninety-nine".