12640557 has 4 divisors (see below), whose sum is σ = 16854080. Its totient is φ = 8427036.

The previous prime is 12640543. The next prime is 12640561. The reversal of 12640557 is 75504621.

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.

It is not a de Polignac number, because 12640557 - 2⁷ = 12640429 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 (12640517) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2106757 + ... + 2106762.

It is an arithmetic number, because the mean of its divisors is an integer number (4213520).

Almost surely, 2^12640557 is an apocalyptic number.

It is an amenable number.

12640557 is a deficient number, since it is larger than the sum of its proper divisors (4213523).

12640557 is an equidigital number, since it uses as much as digits as its factorization.

12640557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4213522.

The product of its (nonzero) digits is 8400, while the sum is 30.

The square root of 12640557 is about 3555.3561003084. The cubic root of 12640557 is about 232.9460785045.

The spelling of 12640557 in words is "twelve million, six hundred forty thousand, five hundred fifty-seven".