21212201999 has 4 divisors (see below), whose sum is σ = 21214338936. Its totient is φ = 21210065064.

The previous prime is 21212201963. The next prime is 21212202041. The reversal of 21212201999 is 99910221212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21212201999 - 2²⁰ = 21211153423 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 (21212201399) 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, 1053509 + ... + 1073454.

It is an arithmetic number, because the mean of its divisors is an integer number (5303584734).

Almost surely, 2^21212201999 is an apocalyptic number.

21212201999 is a deficient number, since it is larger than the sum of its proper divisors (2136937).

21212201999 is an equidigital number, since it uses as much as digits as its factorization.

21212201999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2136936.

The product of its (nonzero) digits is 11664, while the sum is 38.

The spelling of 21212201999 in words is "twenty-one billion, two hundred twelve million, two hundred one thousand, nine hundred ninety-nine".