1665666656 has 24 divisors (see below), whose sum is σ = 3359266344. Its totient is φ = 812519680.

The previous prime is 1665666631. The next prime is 1665666661. The reversal of 1665666656 is 6566665661.

It is a junction number, because it is equal to n+sod(n) for n = 1665666598 and 1665666607.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 633470 + ... + 636093.

It is an arithmetic number, because the mean of its divisors is an integer number (139969431).

Almost surely, 2^1665666656 is an apocalyptic number.

1665666656 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1665666656 is an abundant number, since it is smaller than the sum of its proper divisors (1693599688).

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

1665666656 is a wasteful number, since it uses less digits than its factorization.

1665666656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1269614 (or 1269606 counting only the distinct ones).

The product of its digits is 6998400, while the sum is 53.

The square root of 1665666656 is about 40812.5796293251. The cubic root of 1665666656 is about 1185.3939253050.

The spelling of 1665666656 in words is "one billion, six hundred sixty-five million, six hundred sixty-six thousand, six hundred fifty-six".