1266399816 has 64 divisors (see below), whose sum is σ = 3468441600. Its totient is φ = 382132800.

The previous prime is 1266399809. The next prime is 1266399877. The reversal of 1266399816 is 6189936621.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53061 + ... + 73131.

It is an arithmetic number, because the mean of its divisors is an integer number (54194400).

Almost surely, 2^1266399816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1266399816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1734220800).

1266399816 is an abundant number, since it is smaller than the sum of its proper divisors (2202041784).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1266399816 is a wasteful number, since it uses less digits than its factorization.

1266399816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20330 (or 20326 counting only the distinct ones).

The product of its digits is 839808, while the sum is 51.

The square root of 1266399816 is about 35586.5117144122. The cubic root of 1266399816 is about 1081.9078691045.

The spelling of 1266399816 in words is "one billion, two hundred sixty-six million, three hundred ninety-nine thousand, eight hundred sixteen".