1665051665 has 4 divisors (see below), whose sum is σ = 1998062004. Its totient is φ = 1332041328.

The previous prime is 1665051659. The next prime is 1665051667. The reversal of 1665051665 is 5661505661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5661505661 = 7 ⋅808786523.

It can be written as a sum of positive squares in 2 ways, for example, as 714439441 + 950612224 = 26729^2 + 30832^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665051665 - 2¹² = 1665047569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1665051667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166505162 + ... + 166505171.

It is an arithmetic number, because the mean of its divisors is an integer number (499515501).

Almost surely, 2^1665051665 is an apocalyptic number.

It is an amenable number.

1665051665 is a deficient number, since it is larger than the sum of its proper divisors (333010339).

1665051665 is an equidigital number, since it uses as much as digits as its factorization.

1665051665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333010338.

The product of its (nonzero) digits is 162000, while the sum is 41.

The square root of 1665051665 is about 40805.0446023528. The cubic root of 1665051665 is about 1185.2480184931.

The spelling of 1665051665 in words is "one billion, six hundred sixty-five million, fifty-one thousand, six hundred sixty-five".