12656721 has 48 divisors (see below), whose sum is σ = 22522752. Its totient is φ = 6167040.

The previous prime is 12656713. The next prime is 12656737. The reversal of 12656721 is 12765621.

12656721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 12656721 - 2³ = 12656713 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12656221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 43051 + ... + 43343.

It is an arithmetic number, because the mean of its divisors is an integer number (469224).

Almost surely, 2^12656721 is an apocalyptic number.

12656721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

12656721 is a deficient number, since it is larger than the sum of its proper divisors (9866031).

12656721 is a wasteful number, since it uses less digits than its factorization.

12656721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342 (or 331 counting only the distinct ones).

The product of its digits is 5040, while the sum is 30.

The square root of 12656721 is about 3557.6285640859. The cubic root of 12656721 is about 233.0453287877.

Subtracting 12656721 from its reverse (12765621), we obtain a square (108900 = 330²).

The spelling of 12656721 in words is "twelve million, six hundred fifty-six thousand, seven hundred twenty-one".