12819781 has 4 divisors (see below), whose sum is σ = 13805932. Its totient is φ = 11833632.

The previous prime is 12819773. The next prime is 12819841. The reversal of 12819781 is 18791821.

12819781 is digitally balanced in base 2, 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.

It can be written as a sum of positive squares in 2 ways, for example, as 3572100 + 9247681 = 1890^2 + 3041^2 .

It is a cyclic number.

It is not a de Polignac number, because 12819781 - 2³ = 12819773 is a prime.

It is a super-2 number, since 2×12819781² = 328693569775922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 12819781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12819181) 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, 493056 + ... + 493081.

It is an arithmetic number, because the mean of its divisors is an integer number (3451483).

Almost surely, 2^12819781 is an apocalyptic number.

It is an amenable number.

12819781 is a deficient number, since it is larger than the sum of its proper divisors (986151).

12819781 is an equidigital number, since it uses as much as digits as its factorization.

12819781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 986150.

The product of its digits is 8064, while the sum is 37.

The square root of 12819781 is about 3580.4721755657. The cubic root of 12819781 is about 234.0418570264.

The spelling of 12819781 in words is "twelve million, eight hundred nineteen thousand, seven hundred eighty-one".