1666666665 has 32 divisors (see below), whose sum is σ = 3043052160. Its totient is φ = 864862272.

The previous prime is 1666666649. The next prime is 1666666667. The reversal of 1666666665 is 5666666661.

It is not a de Polignac number, because 1666666665 - 2⁴ = 1666666649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666666667) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 161839 + ... + 171828.

It is an arithmetic number, because the mean of its divisors is an integer number (95095380).

Almost surely, 2^1666666665 is an apocalyptic number.

1666666665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1666666665 is a deficient number, since it is larger than the sum of its proper divisors (1376385495).

1666666665 is a wasteful number, since it uses less digits than its factorization.

1666666665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333718 (or 333712 counting only the distinct ones).

The product of its digits is 8398080, while the sum is 54.

The square root of 1666666665 is about 40824.8290259739. The cubic root of 1666666665 is about 1185.6311011015.

It can be divided in two parts, 1 and 666666665, that added together give a palindrome (666666666).

The spelling of 1666666665 in words is "one billion, six hundred sixty-six million, six hundred sixty-six thousand, six hundred sixty-five".