1266564781 has 2 divisors, whose sum is σ = 1266564782. Its totient is φ = 1266564780.

The previous prime is 1266564721. The next prime is 1266564853. The reversal of 1266564781 is 1874656621.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1058916681 + 207648100 = 32541^2 + 14410^2 .

It is a cyclic number.

It is not a de Polignac number, because 1266564781 - 2¹⁹ = 1266040493 is a prime.

It is a super-2 number, since 2×1266564781² = 3208372688939155922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1266564701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633282390 + 633282391.

It is an arithmetic number, because the mean of its divisors is an integer number (633282391).

Almost surely, 2^1266564781 is an apocalyptic number.

It is an amenable number.

1266564781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1266564781 is an equidigital number, since it uses as much as digits as its factorization.

1266564781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 483840, while the sum is 46.

The square root of 1266564781 is about 35588.8294412727. The cubic root of 1266564781 is about 1081.9548445752.

The spelling of 1266564781 in words is "one billion, two hundred sixty-six million, five hundred sixty-four thousand, seven hundred eighty-one".