1665065561 has 8 divisors (see below), whose sum is σ = 1767090024. Its totient is φ = 1563494400.

The previous prime is 1665065557. The next prime is 1665065587. The reversal of 1665065561 is 1655605661.

It can be written as a sum of positive squares in 4 ways, for example, as 627001600 + 1038063961 = 25040^2 + 32219^2 .

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 1665065561 - 2² = 1665065557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1665065261) 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, 105740 + ... + 120461.

It is an arithmetic number, because the mean of its divisors is an integer number (220886253).

Almost surely, 2^1665065561 is an apocalyptic number.

It is an amenable number.

1665065561 is a deficient number, since it is larger than the sum of its proper divisors (102024463).

1665065561 is a wasteful number, since it uses less digits than its factorization.

1665065561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226651.

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

The square root of 1665065561 is about 40805.2148750622. The cubic root of 1665065561 is about 1185.2513157202.

The spelling of 1665065561 in words is "one billion, six hundred sixty-five million, sixty-five thousand, five hundred sixty-one".