665855856 has 40 divisors (see below), whose sum is σ = 1911254160. Its totient is φ = 221951808.

The previous prime is 665855843. The next prime is 665855891. The reversal of 665855856 is 658558566.

665855856 is a `hidden beast` number, since 6 + 6 + 58 + 5 + 585 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 770235 + ... + 771098.

It is an arithmetic number, because the mean of its divisors is an integer number (47781354).

Almost surely, 2^665855856 is an apocalyptic number.

It is an amenable number.

665855856 is an abundant number, since it is smaller than the sum of its proper divisors (1245398304).

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

665855856 is a wasteful number, since it uses less digits than its factorization.

665855856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1541350 (or 1541338 counting only the distinct ones).

The product of its digits is 8640000, while the sum is 54.

The square root of 665855856 is about 25804.1829167288. The cubic root of 665855856 is about 873.2261668837.

The spelling of 665855856 in words is "six hundred sixty-five million, eight hundred fifty-five thousand, eight hundred fifty-six".