12121999 has 4 divisors (see below), whose sum is σ = 12233320. Its totient is φ = 12010680.

The previous prime is 12121987. The next prime is 12122009. The reversal of 12121999 is 99912121.

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 12121999 - 2⁷ = 12121871 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 (12121939) 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, 55497 + ... + 55714.

It is an arithmetic number, because the mean of its divisors is an integer number (3058330).

Almost surely, 2^12121999 is an apocalyptic number.

12121999 is a deficient number, since it is larger than the sum of its proper divisors (111321).

12121999 is a wasteful number, since it uses less digits than its factorization.

12121999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111320.

The product of its digits is 2916, while the sum is 34.

The square root of 12121999 is about 3481.6661241423. Note that the first 3 decimals coincide. The cubic root of 12121999 is about 229.7160895105.

The spelling of 12121999 in words is "twelve million, one hundred twenty-one thousand, nine hundred ninety-nine".