12643721 has 8 divisors (see below), whose sum is σ = 13888320. Its totient is φ = 11457072.

The previous prime is 12643717. The next prime is 12643723. The reversal of 12643721 is 12734621.

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 12643721 - 2² = 12643717 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (12643723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14030 + ... + 14903.

It is an arithmetic number, because the mean of its divisors is an integer number (1736040).

Almost surely, 2^12643721 is an apocalyptic number.

It is an amenable number.

12643721 is a deficient number, since it is larger than the sum of its proper divisors (1244599).

12643721 is a wasteful number, since it uses less digits than its factorization.

12643721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28975.

The product of its digits is 2016, while the sum is 26.

The square root of 12643721 is about 3555.8010349287. The cubic root of 12643721 is about 232.9655127722.

The spelling of 12643721 in words is "twelve million, six hundred forty-three thousand, seven hundred twenty-one".