12640991 has 6 divisors (see below), whose sum is σ = 13894776. Its totient is φ = 11491700.

The previous prime is 12640973. The next prime is 12640993. The reversal of 12640991 is 19904621.

It is a de Polignac number, because none of the positive numbers 2^k-12640991 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 (12640993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 52115 + ... + 52356.

It is an arithmetic number, because the mean of its divisors is an integer number (2315796).

Almost surely, 2^12640991 is an apocalyptic number.

12640991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

12640991 is a deficient number, since it is larger than the sum of its proper divisors (1253785).

12640991 is a wasteful number, since it uses less digits than its factorization.

12640991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104493 (or 104482 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 12640991 is about 3555.4171344583. The cubic root of 12640991 is about 232.9487444588.

It can be divided in two parts, 12640 and 991, that added together give a palindrome (13631).

The spelling of 12640991 in words is "twelve million, six hundred forty thousand, nine hundred ninety-one".