1266815880 has 384 divisors, whose sum is σ = 4801680000. Its totient is φ = 286433280.

The previous prime is 1266815813. The next prime is 1266815881. The reversal of 1266815880 is 885186621.

1266815880 is a `hidden beast` number, since 1 + 2 + 6 + 68 + 1 + 588 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (1266815881) 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 in 95 ways as a sum of consecutive naturals, for example, 8502046 + ... + 8502194.

It is an arithmetic number, because the mean of its divisors is an integer number (12504375).

Almost surely, 2^1266815880 is an apocalyptic number.

1266815880 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1266815880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2400840000).

1266815880 is an abundant number, since it is smaller than the sum of its proper divisors (3534864120).

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

1266815880 is a wasteful number, since it uses less digits than its factorization.

1266815880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 309 (or 302 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 45.

The square root of 1266815880 is about 35592.3570447364. The cubic root of 1266815880 is about 1082.0263397544.

The spelling of 1266815880 in words is "one billion, two hundred sixty-six million, eight hundred fifteen thousand, eight hundred eighty".