12781649 has 2 divisors, whose sum is σ = 12781650. Its totient is φ = 12781648.

The previous prime is 12781631. The next prime is 12781669. The reversal of 12781649 is 94618721.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12780625 + 1024 = 3575^2 + 32^2 .

It is a cyclic number.

It is not a de Polignac number, because 12781649 - 2¹² = 12777553 is a prime.

It is a super-4 number, since 4×12781649⁴ (a number of 30 digits) contains 4444 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (12781609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6390824 + 6390825.

It is an arithmetic number, because the mean of its divisors is an integer number (6390825).

Almost surely, 2^12781649 is an apocalyptic number.

It is an amenable number.

12781649 is a deficient number, since it is larger than the sum of its proper divisors (1).

12781649 is an equidigital number, since it uses as much as digits as its factorization.

12781649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 38.

The square root of 12781649 is about 3575.1432139147. The cubic root of 12781649 is about 233.8095767384.

The spelling of 12781649 in words is "twelve million, seven hundred eighty-one thousand, six hundred forty-nine".