12640491 has 24 divisors (see below), whose sum is σ = 19890000. Its totient is φ = 7705152.

The previous prime is 12640489. The next prime is 12640499. The reversal of 12640491 is 19404621.

12640491 is a `hidden beast` number, since 12 + 640 + 4 + 9 + 1 = 666.

It is not a de Polignac number, because 12640491 - 2¹ = 12640489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (12640499) 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 23 ways as a sum of consecutive naturals, for example, 3685 + ... + 6233.

It is an arithmetic number, because the mean of its divisors is an integer number (828750).

Almost surely, 2^12640491 is an apocalyptic number.

12640491 is a deficient number, since it is larger than the sum of its proper divisors (7249509).

12640491 is a wasteful number, since it uses less digits than its factorization.

12640491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2603 (or 2600 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 12640491 is about 3555.3468185256. The cubic root of 12640491 is about 232.9456730776.

It can be divided in two parts, 12640 and 491, that added together give a palindrome (13131).

The spelling of 12640491 in words is "twelve million, six hundred forty thousand, four hundred ninety-one".