1665506665 has 8 divisors (see below), whose sum is σ = 2018396808. Its totient is φ = 1319212800.

The previous prime is 1665506629. The next prime is 1665506669. The reversal of 1665506665 is 5666055661.

It can be written as a sum of positive squares in 4 ways, for example, as 392158809 + 1273347856 = 19803^2 + 35684^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1665506665 - 2⁷ = 1665506537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1665506669) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1648512 + ... + 1649521.

It is an arithmetic number, because the mean of its divisors is an integer number (252299601).

Almost surely, 2^1665506665 is an apocalyptic number.

It is an amenable number.

1665506665 is a deficient number, since it is larger than the sum of its proper divisors (352890143).

1665506665 is a wasteful number, since it uses less digits than its factorization.

1665506665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3298139.

The product of its (nonzero) digits is 972000, while the sum is 46.

The square root of 1665506665 is about 40810.6195125729. The cubic root of 1665506665 is about 1185.3559708457.

The spelling of 1665506665 in words is "one billion, six hundred sixty-five million, five hundred six thousand, six hundred sixty-five".