1665555666 has 32 divisors (see below), whose sum is σ = 3539125440. Its totient is φ = 521551296.

The previous prime is 1665555653. The next prime is 1665555673. The reversal of 1665555666 is 6665555661.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 122916 + ... + 135791.

It is an arithmetic number, because the mean of its divisors is an integer number (110597670).

Almost surely, 2^1665555666 is an apocalyptic number.

1665555666 is an abundant number, since it is smaller than the sum of its proper divisors (1873569774).

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

1665555666 is a wasteful number, since it uses less digits than its factorization.

1665555666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258778.

The product of its digits is 4860000, while the sum is 51.

The square root of 1665555666 is about 40811.2198543489. The cubic root of 1665555666 is about 1185.3675955481.

The spelling of 1665555666 in words is "one billion, six hundred sixty-five million, five hundred fifty-five thousand, six hundred sixty-six".