1266781 has 2 divisors, whose sum is σ = 1266782. Its totient is φ = 1266780.

The previous prime is 1266779. The next prime is 1266799. The reversal of 1266781 is 1876621.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1265625 + 1156 = 1125^2 + 34^2 .

It is a cyclic number.

It is not a de Polignac number, because 1266781 - 2¹ = 1266779 is a prime.

It is a super-5 number, since 5×1266781⁵ (a number of 32 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

Together with 1266779, it forms a pair of twin primes.

It is a nialpdrome in base 12.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1266731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633390 + 633391.

It is an arithmetic number, because the mean of its divisors is an integer number (633391).

2^1266781 is an apocalyptic number.

It is an amenable number.

1266781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1266781 is an equidigital number, since it uses as much as digits as its factorization.

1266781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4032, while the sum is 31.

The square root of 1266781 is about 1125.5136605124. The cubic root of 1266781 is about 108.2016408970.

The spelling of 1266781 in words is "one million, two hundred sixty-six thousand, seven hundred eighty-one".