12665978 has 16 divisors (see below), whose sum is σ = 20519520. Its totient is φ = 5828976.

The previous prime is 12665959. The next prime is 12665987. The reversal of 12665978 is 87956621.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15701 + ... + 16487.

It is an arithmetic number, because the mean of its divisors is an integer number (1282470).

Almost surely, 2^12665978 is an apocalyptic number.

12665978 is a deficient number, since it is larger than the sum of its proper divisors (7853542).

12665978 is a wasteful number, since it uses less digits than its factorization.

12665978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1421.

The product of its digits is 181440, while the sum is 44.

The square root of 12665978 is about 3558.9293333810. The cubic root of 12665978 is about 233.1021306213.

The spelling of 12665978 in words is "twelve million, six hundred sixty-five thousand, nine hundred seventy-eight".