1645769665 has 4 divisors (see below), whose sum is σ = 1974923604. Its totient is φ = 1316615728.

The previous prime is 1645769663. The next prime is 1645769681. The reversal of 1645769665 is 5669675461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5669675461 = 281 ⋅20176781.

It can be written as a sum of positive squares in 2 ways, for example, as 1099519281 + 546250384 = 33159^2 + 23372^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645769665 - 2¹ = 1645769663 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1645769663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164576962 + ... + 164576971.

It is an arithmetic number, because the mean of its divisors is an integer number (493730901).

Almost surely, 2^1645769665 is an apocalyptic number.

It is an amenable number.

1645769665 is a deficient number, since it is larger than the sum of its proper divisors (329153939).

1645769665 is an equidigital number, since it uses as much as digits as its factorization.

1645769665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329153938.

The product of its digits is 8164800, while the sum is 55.

The square root of 1645769665 is about 40568.0867801280. The cubic root of 1645769665 is about 1180.6550191233.

The spelling of 1645769665 in words is "one billion, six hundred forty-five million, seven hundred sixty-nine thousand, six hundred sixty-five".