1266435521 has 4 divisors (see below), whose sum is σ = 1363853652. Its totient is φ = 1169017392.

The previous prime is 1266435437. The next prime is 1266435551. The reversal of 1266435521 is 1255346621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1255346621 = 367 ⋅3420563.

It can be written as a sum of positive squares in 2 ways, for example, as 568154896 + 698280625 = 23836^2 + 26425^2 .

It is a cyclic number.

It is not a de Polignac number, because 1266435521 - 2¹⁰ = 1266434497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1266435551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48709046 + ... + 48709071.

It is an arithmetic number, because the mean of its divisors is an integer number (340963413).

Almost surely, 2^1266435521 is an apocalyptic number.

It is an amenable number.

1266435521 is a deficient number, since it is larger than the sum of its proper divisors (97418131).

1266435521 is an equidigital number, since it uses as much as digits as its factorization.

1266435521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97418130.

The product of its digits is 43200, while the sum is 35.

The square root of 1266435521 is about 35587.0133756684. The cubic root of 1266435521 is about 1081.9180368143.

Subtracting from 1266435521 its reverse (1255346621), we obtain a square (11088900 = 3330²).

The spelling of 1266435521 in words is "one billion, two hundred sixty-six million, four hundred thirty-five thousand, five hundred twenty-one".