12640861 has 4 divisors (see below), whose sum is σ = 12650112. Its totient is φ = 12631612.

The previous prime is 12640841. The next prime is 12640867. The reversal of 12640861 is 16804621.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 12640861 - 2⁵ = 12640829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12640867) 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 3 ways as a sum of consecutive naturals, for example, 2125 + ... + 5458.

It is an arithmetic number, because the mean of its divisors is an integer number (3162528).

Almost surely, 2^12640861 is an apocalyptic number.

It is an amenable number.

12640861 is a deficient number, since it is larger than the sum of its proper divisors (9251).

12640861 is an equidigital number, since it uses as much as digits as its factorization.

12640861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9250.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 12640861 is about 3555.3988524496. The cubic root of 12640861 is about 232.9479459075.

The spelling of 12640861 in words is "twelve million, six hundred forty thousand, eight hundred sixty-one".