12811978 has 4 divisors (see below), whose sum is σ = 19217970. Its totient is φ = 6405988.

The previous prime is 12811973. The next prime is 12811987. The reversal of 12811978 is 87911821.

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

It can be written as a sum of positive squares in only one way, i.e., 10387729 + 2424249 = 3223^2 + 1557^2 .

It is not an unprimeable number, because it can be changed into a prime (12811973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3202993 + ... + 3202996.

Almost surely, 2^12811978 is an apocalyptic number.

12811978 is a deficient number, since it is larger than the sum of its proper divisors (6405992).

12811978 is an equidigital number, since it uses as much as digits as its factorization.

12811978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6405991.

The product of its digits is 8064, while the sum is 37.

The square root of 12811978 is about 3579.3823489535. The cubic root of 12811978 is about 233.9943627346.

The spelling of 12811978 in words is "twelve million, eight hundred eleven thousand, nine hundred seventy-eight".