12123991 has 4 divisors (see below), whose sum is σ = 13226184. Its totient is φ = 11021800.

The previous prime is 12123977. The next prime is 12124061. The reversal of 12123991 is 19932121.

12123991 = 1419² + 1420² + ... + 1424².

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 12123991 - 2⁵ = 12123959 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 (12124991) 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 3 ways as a sum of consecutive naturals, for example, 551080 + ... + 551101.

It is an arithmetic number, because the mean of its divisors is an integer number (3306546).

Almost surely, 2^12123991 is an apocalyptic number.

12123991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

12123991 is a deficient number, since it is larger than the sum of its proper divisors (1102193).

12123991 is a wasteful number, since it uses less digits than its factorization.

12123991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1102192.

The product of its digits is 972, while the sum is 28.

The square root of 12123991 is about 3481.9521823253. The cubic root of 12123991 is about 229.7286718519.

The spelling of 12123991 in words is "twelve million, one hundred twenty-three thousand, nine hundred ninety-one".