126666781 has 2 divisors, whose sum is σ = 126666782. Its totient is φ = 126666780.

The previous prime is 126666763. The next prime is 126666791. The reversal of 126666781 is 187666621.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 93431556 + 33235225 = 9666^2 + 5765^2 .

It is a cyclic number.

It is not a de Polignac number, because 126666781 - 2²¹ = 124569629 is a prime.

It is a super-3 number, since 3×126666781³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (126666721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 63333390 + 63333391.

It is an arithmetic number, because the mean of its divisors is an integer number (63333391).

Almost surely, 2^126666781 is an apocalyptic number.

It is an amenable number.

126666781 is a deficient number, since it is larger than the sum of its proper divisors (1).

126666781 is an equidigital number, since it uses as much as digits as its factorization.

126666781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 43.

The square root of 126666781 is about 11254.6337568132. The cubic root of 126666781 is about 502.2125692988.

The spelling of 126666781 in words is "one hundred twenty-six million, six hundred sixty-six thousand, seven hundred eighty-one".