12391731 has 24 divisors (see below), whose sum is σ = 20184080. Its totient is φ = 7508160.

The previous prime is 12391727. The next prime is 12391739. The reversal of 12391731 is 13719321.

It is not a de Polignac number, because 12391731 - 2² = 12391727 is a prime.

It is a super-2 number, since 2×12391731² = 307109994352722, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 12391695 and 12391704.

It is not an unprimeable number, because it can be changed into a prime (12391739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1371 + ... + 5163.

Almost surely, 2^12391731 is an apocalyptic number.

12391731 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

12391731 is a deficient number, since it is larger than the sum of its proper divisors (7792349).

12391731 is a wasteful number, since it uses less digits than its factorization.

12391731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3824 (or 3807 counting only the distinct ones).

The product of its digits is 1134, while the sum is 27.

The square root of 12391731 is about 3520.1890574229. The cubic root of 12391731 is about 231.4074441815.

The spelling of 12391731 in words is "twelve million, three hundred ninety-one thousand, seven hundred thirty-one".