1266726661 has 8 divisors (see below), whose sum is σ = 1357401024. Its totient is φ = 1177848000.

The previous prime is 1266726631. The next prime is 1266726667. The reversal of 1266726661 is 1666276621.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1266726661 - 2¹⁹ = 1266202373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1266726667) 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 in 7 ways as a sum of consecutive naturals, for example, 447465 + ... + 450286.

It is an arithmetic number, because the mean of its divisors is an integer number (169675128).

Almost surely, 2^1266726661 is an apocalyptic number.

It is an amenable number.

1266726661 is a deficient number, since it is larger than the sum of its proper divisors (90674363).

1266726661 is an equidigital number, since it uses as much as digits as its factorization.

1266726661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 897851.

The product of its digits is 217728, while the sum is 43.

The square root of 1266726661 is about 35591.1036777451. The cubic root of 1266726661 is about 1082.0009375956. Note that the first 3 decimals are identical.

The spelling of 1266726661 in words is "one billion, two hundred sixty-six million, seven hundred twenty-six thousand, six hundred sixty-one".