12664781 has 2 divisors, whose sum is σ = 12664782. Its totient is φ = 12664780.

The previous prime is 12664741. The next prime is 12664807. The reversal of 12664781 is 18746621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8462281 + 4202500 = 2909^2 + 2050^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12664781 is a prime.

It is a super-2 number, since 2×12664781² = 320793355555922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12664741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6332390 + 6332391.

It is an arithmetic number, because the mean of its divisors is an integer number (6332391).

Almost surely, 2^12664781 is an apocalyptic number.

It is an amenable number.

12664781 is a deficient number, since it is larger than the sum of its proper divisors (1).

12664781 is an equidigital number, since it uses as much as digits as its factorization.

12664781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 35.

The square root of 12664781 is about 3558.7611608536. The cubic root of 12664781 is about 233.0947872736.

The spelling of 12664781 in words is "twelve million, six hundred sixty-four thousand, seven hundred eighty-one".