665851856 has 40 divisors (see below), whose sum is σ = 1307249664. Its totient is φ = 328527360.

The previous prime is 665851853. The next prime is 665851859. The reversal of 665851856 is 658158566.

It is an interprime number because it is at equal distance from previous prime (665851853) and next prime (665851859).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665851853) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 427976 + ... + 429528.

Almost surely, 2^665851856 is an apocalyptic number.

It is an amenable number.

665851856 is a deficient number, since it is larger than the sum of its proper divisors (641397808).

665851856 is a wasteful number, since it uses less digits than its factorization.

665851856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1899 (or 1893 counting only the distinct ones).

The product of its digits is 1728000, while the sum is 50.

The square root of 665851856 is about 25804.1054097987. The cubic root of 665851856 is about 873.2244183012.

The spelling of 665851856 in words is "six hundred sixty-five million, eight hundred fifty-one thousand, eight hundred fifty-six".