12643981 has 8 divisors (see below), whose sum is σ = 14483840. Its totient is φ = 10812528.

The previous prime is 12643933. The next prime is 12643999. The reversal of 12643981 is 18934621.

12643981 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 cyclic number.

It is not a de Polignac number, because 12643981 - 2⁹ = 12643469 is a prime.

It is a super-2 number, since 2×12643981² = 319740511056722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12643901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1555 + ... + 5263.

It is an arithmetic number, because the mean of its divisors is an integer number (1810480).

Almost surely, 2^12643981 is an apocalyptic number.

It is an amenable number.

12643981 is a deficient number, since it is larger than the sum of its proper divisors (1839859).

12643981 is an equidigital number, since it uses as much as digits as its factorization.

12643981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4203.

The product of its digits is 10368, while the sum is 34.

The square root of 12643981 is about 3555.8375947166. The cubic root of 12643981 is about 232.9671096286.

The spelling of 12643981 in words is "twelve million, six hundred forty-three thousand, nine hundred eighty-one".