1665665666 has 16 divisors (see below), whose sum is σ = 3005712960. Its totient is φ = 676285200.

The previous prime is 1665665657. The next prime is 1665665671. The reversal of 1665665666 is 6665665661.

It is a super-2 number, since 2×1665665666² = 5548884221782447112, which contains 22 as substring.

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, 3130685 + ... + 3131216.

It is an arithmetic number, because the mean of its divisors is an integer number (187857060).

Almost surely, 2^1665665666 is an apocalyptic number.

1665665666 is a deficient number, since it is larger than the sum of its proper divisors (1340047294).

1665665666 is a wasteful number, since it uses less digits than its factorization.

1665665666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6261929.

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

The square root of 1665665666 is about 40812.5675007099. The cubic root of 1665665666 is about 1185.3936904560.

The spelling of 1665665666 in words is "one billion, six hundred sixty-five million, six hundred sixty-five thousand, six hundred sixty-six".