666761856 has 64 divisors (see below), whose sum is σ = 1773796320. Its totient is φ = 221914112.

The previous prime is 666761807. The next prime is 666761869. The reversal of 666761856 is 658167666.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

It is a junction number, because it is equal to n+sod(n) for n = 666761799 and 666761808.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 445846 + ... + 447338.

Almost surely, 2^666761856 is an apocalyptic number.

It is an amenable number.

666761856 is an abundant number, since it is smaller than the sum of its proper divisors (1107034464).

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

666761856 is a wasteful number, since it uses less digits than its factorization.

666761856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2673 (or 2661 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 51.

The square root of 666761856 is about 25821.7322424349. The cubic root of 666761856 is about 873.6220405286.

The spelling of 666761856 in words is "six hundred sixty-six million, seven hundred sixty-one thousand, eight hundred fifty-six".