1665155609 has 8 divisors (see below), whose sum is σ = 1805281800. Its totient is φ = 1526749056.

The previous prime is 1665155599. The next prime is 1665155617. The reversal of 1665155609 is 9065515661.

It can be written as a sum of positive squares in 4 ways, for example, as 107584 + 1665048025 = 328^2 + 40805^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1665155609 - 2⁸ = 1665155353 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1665155609.

It is not an unprimeable number, because it can be changed into a prime (1665155689) 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, 427892 + ... + 431765.

It is an arithmetic number, because the mean of its divisors is an integer number (225660225).

Almost surely, 2^1665155609 is an apocalyptic number.

It is an amenable number.

1665155609 is a deficient number, since it is larger than the sum of its proper divisors (140126191).

1665155609 is a wasteful number, since it uses less digits than its factorization.

1665155609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 859819.

The product of its (nonzero) digits is 243000, while the sum is 44.

The square root of 1665155609 is about 40806.3182485262. The cubic root of 1665155609 is about 1185.2726817631.

The spelling of 1665155609 in words is "one billion, six hundred sixty-five million, one hundred fifty-five thousand, six hundred nine".