1288780665 has 16 divisors (see below), whose sum is σ = 2063361600. Its totient is φ = 686912192.

The previous prime is 1288780657. The next prime is 1288780667. The reversal of 1288780665 is 5660878821.

It is a cyclic number.

It is not a de Polignac number, because 1288780665 - 2³ = 1288780657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1288780667) by changing a digit.

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, 2250 + ... + 50819.

It is an arithmetic number, because the mean of its divisors is an integer number (128960100).

Almost surely, 2^1288780665 is an apocalyptic number.

1288780665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1288780665 is a deficient number, since it is larger than the sum of its proper divisors (774580935).

1288780665 is a wasteful number, since it uses less digits than its factorization.

1288780665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54696.

The product of its (nonzero) digits is 1290240, while the sum is 51.

The square root of 1288780665 is about 35899.5914322155. The cubic root of 1288780665 is about 1088.2441401848.

The spelling of 1288780665 in words is "one billion, two hundred eighty-eight million, seven hundred eighty thousand, six hundred sixty-five".