1661662165 has 8 divisors (see below), whose sum is σ = 1997251128. Its totient is φ = 1327158720.

The previous prime is 1661662147. The next prime is 1661662169. The reversal of 1661662165 is 5612661661.

It can be written as a sum of positive squares in 4 ways, for example, as 215913636 + 1445748529 = 14694^2 + 38023^2 .

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

It is not a de Polignac number, because 1661662165 - 2⁵ = 1661662133 is a prime.

It is a super-2 number, since 2×1661662165² = 5522242301184974450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661662169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 268006 + ... + 274135.

It is an arithmetic number, because the mean of its divisors is an integer number (249656391).

Almost surely, 2^1661662165 is an apocalyptic number.

It is an amenable number.

1661662165 is a deficient number, since it is larger than the sum of its proper divisors (335588963).

1661662165 is an equidigital number, since it uses as much as digits as its factorization.

1661662165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542759.

The product of its digits is 77760, while the sum is 40.

The square root of 1661662165 is about 40763.4905890062. The cubic root of 1661662165 is about 1184.4432131796.

The spelling of 1661662165 in words is "one billion, six hundred sixty-one million, six hundred sixty-two thousand, one hundred sixty-five".