12143991 has 4 divisors (see below), whose sum is σ = 16191992. Its totient is φ = 8095992.

The previous prime is 12143981. The next prime is 12143993. The reversal of 12143991 is 19934121.

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

It is not a de Polignac number, because 12143991 - 2⁶ = 12143927 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 (12143993) 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, 2023996 + ... + 2024001.

It is an arithmetic number, because the mean of its divisors is an integer number (4047998).

Almost surely, 2^12143991 is an apocalyptic number.

12143991 is a deficient number, since it is larger than the sum of its proper divisors (4048001).

12143991 is an equidigital number, since it uses as much as digits as its factorization.

12143991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4048000.

The product of its digits is 1944, while the sum is 30.

The square root of 12143991 is about 3484.8229510264. The cubic root of 12143991 is about 229.8549242637.

The spelling of 12143991 in words is "twelve million, one hundred forty-three thousand, nine hundred ninety-one".