665851559 has 4 divisors (see below), whose sum is σ = 666024960. Its totient is φ = 665678160.

The previous prime is 665851547. The next prime is 665851567. The reversal of 665851559 is 955158566.

665851559 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665851559 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 (665851859) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80807 + ... + 88664.

It is an arithmetic number, because the mean of its divisors is an integer number (166506240).

Almost surely, 2^665851559 is an apocalyptic number.

665851559 is a deficient number, since it is larger than the sum of its proper divisors (173401).

665851559 is a wasteful number, since it uses less digits than its factorization.

665851559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173400.

The product of its digits is 1620000, while the sum is 50.

The square root of 665851559 is about 25804.0996548998. The cubic root of 665851559 is about 873.2242884687.

The spelling of 665851559 in words is "six hundred sixty-five million, eight hundred fifty-one thousand, five hundred fifty-nine".