12640381 has 4 divisors (see below), whose sum is σ = 13612732. Its totient is φ = 11668032.

The previous prime is 12640373. The next prime is 12640393. The reversal of 12640381 is 18304621.

12640381 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18304621 = 281 ⋅65141.

It can be written as a sum of positive squares in 2 ways, for example, as 737881 + 11902500 = 859^2 + 3450^2 .

It is a cyclic number.

It is not a de Polignac number, because 12640381 - 2³ = 12640373 is a prime.

It is a super-2 number, since 2×12640381² = 319558463650322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12640351) 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, 486156 + ... + 486181.

It is an arithmetic number, because the mean of its divisors is an integer number (3403183).

Almost surely, 2^12640381 is an apocalyptic number.

It is an amenable number.

12640381 is a deficient number, since it is larger than the sum of its proper divisors (972351).

12640381 is an equidigital number, since it uses as much as digits as its factorization.

12640381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 972350.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 12640381 is about 3555.3313488337. The cubic root of 12640381 is about 232.9449973628.

The spelling of 12640381 in words is "twelve million, six hundred forty thousand, three hundred eighty-one".