12391978 has 8 divisors (see below), whose sum is σ = 18645120. Its totient is φ = 6176940.

The previous prime is 12391937. The next prime is 12391987. The reversal of 12391978 is 87919321.

12391978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×12391978² = 307122237504968, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 12391978.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8698 + ... + 10021.

It is an arithmetic number, because the mean of its divisors is an integer number (2330640).

Almost surely, 2^12391978 is an apocalyptic number.

12391978 is a deficient number, since it is larger than the sum of its proper divisors (6253142).

12391978 is a wasteful number, since it uses less digits than its factorization.

12391978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19052.

The product of its digits is 27216, while the sum is 40.

The square root of 12391978 is about 3520.2241405911. The cubic root of 12391978 is about 231.4089816922.

The spelling of 12391978 in words is "twelve million, three hundred ninety-one thousand, nine hundred seventy-eight".