12957781 has 2 divisors, whose sum is σ = 12957782. Its totient is φ = 12957780.

The previous prime is 12957761. The next prime is 12957797. The reversal of 12957781 is 18775921.

12957781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12895281 + 62500 = 3591^2 + 250^2 .

It is an emirp because it is prime and its reverse (18775921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12957781 - 2⁷ = 12957653 is a prime.

It is a super-2 number, since 2×12957781² = 335808176887922, which contains 22 as substring.

It is equal to p₈₄₆₆₇₉ and since 12957781 and 846679 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12957731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6478890 + 6478891.

It is an arithmetic number, because the mean of its divisors is an integer number (6478891).

Almost surely, 2^12957781 is an apocalyptic number.

It is an amenable number.

12957781 is a deficient number, since it is larger than the sum of its proper divisors (1).

12957781 is an equidigital number, since it uses as much as digits as its factorization.

12957781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 40.

The square root of 12957781 is about 3599.6917923622. The cubic root of 12957781 is about 234.8786516999.

The spelling of 12957781 in words is "twelve million, nine hundred fifty-seven thousand, seven hundred eighty-one".