1280780865 has 144 divisors (see below), whose sum is σ = 2809123200. Its totient is φ = 539360640.

The previous prime is 1280780819. The next prime is 1280780873. The reversal of 1280780865 is 5680870821.

It is not a de Polignac number, because 1280780865 - 2¹¹ = 1280778817 is a prime.

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

It is a self number, because there is not a number n which added to its sum of digits gives 1280780865.

It is an unprimeable number.

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 143 ways as a sum of consecutive naturals, for example, 2608270 + ... + 2608760.

It is an arithmetic number, because the mean of its divisors is an integer number (19507800).

Almost surely, 2^1280780865 is an apocalyptic number.

1280780865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1280780865 is an abundant number, since it is smaller than the sum of its proper divisors (1528342335).

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

1280780865 is a wasteful number, since it uses less digits than its factorization.

1280780865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 549 (or 519 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The square root of 1280780865 is about 35787.9988962781. The cubic root of 1280780865 is about 1085.9877927669.

The spelling of 1280780865 in words is "one billion, two hundred eighty million, seven hundred eighty thousand, eight hundred sixty-five".