12721978 has 4 divisors (see below), whose sum is σ = 19082970. Its totient is φ = 6360988.

The previous prime is 12721939. The next prime is 12721999. The reversal of 12721978 is 87912721.

12721978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87912721 = 13 ⋅6762517.

It can be written as a sum of positive squares in only one way, i.e., 9138529 + 3583449 = 3023^2 + 1893^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3180493 + ... + 3180496.

Almost surely, 2^12721978 is an apocalyptic number.

12721978 is a deficient number, since it is larger than the sum of its proper divisors (6360992).

12721978 is an equidigital number, since it uses as much as digits as its factorization.

12721978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6360991.

The product of its digits is 14112, while the sum is 37.

The square root of 12721978 is about 3566.7881910761. The cubic root of 12721978 is about 233.4451631747.

The spelling of 12721978 in words is "twelve million, seven hundred twenty-one thousand, nine hundred seventy-eight".