12991640 has 16 divisors (see below), whose sum is σ = 29231280. Its totient is φ = 5196640.

The previous prime is 12991613. The next prime is 12991661. The reversal of 12991640 is 4619921.

It is a junction number, because it is equal to n+sod(n) for n = 12991597 and 12991606.

It is a congruent number.

It is an unprimeable number.

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, 162356 + ... + 162435.

It is an arithmetic number, because the mean of its divisors is an integer number (1826955).

Almost surely, 2^12991640 is an apocalyptic number.

12991640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

12991640 is an abundant number, since it is smaller than the sum of its proper divisors (16239640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

12991640 is a wasteful number, since it uses less digits than its factorization.

12991640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324802 (or 324798 counting only the distinct ones).

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

The square root of 12991640 is about 3604.3917656104. The cubic root of 12991640 is about 235.0830549947.

It can be divided in two parts, 12991 and 640, that added together give a palindrome (13631).

The spelling of 12991640 in words is "twelve million, nine hundred ninety-one thousand, six hundred forty".