12779991 has 16 divisors (see below), whose sum is σ = 21638400. Its totient is φ = 7302744.

The previous prime is 12779969. The next prime is 12779993. The reversal of 12779991 is 19997721.

It is not a de Polignac number, because 12779991 - 2¹⁰ = 12778967 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12779993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33621 + ... + 33998.

It is an arithmetic number, because the mean of its divisors is an integer number (1352400).

Almost surely, 2^12779991 is an apocalyptic number.

12779991 is a deficient number, since it is larger than the sum of its proper divisors (8858409).

12779991 is an equidigital number, since it uses as much as digits as its factorization.

12779991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67635 (or 67629 counting only the distinct ones).

The product of its digits is 71442, while the sum is 45.

The square root of 12779991 is about 3574.9113275716. The cubic root of 12779991 is about 233.7994665917.

The spelling of 12779991 in words is "twelve million, seven hundred seventy-nine thousand, nine hundred ninety-one".