1005565661 has 4 divisors (see below), whose sum is σ = 1024538652. Its totient is φ = 986592672.

The previous prime is 1005565607. The next prime is 1005565679. The reversal of 1005565661 is 1665655001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1665655001 = 463 ⋅3597527.

It can be written as a sum of positive squares in 2 ways, for example, as 419635225 + 585930436 = 20485^2 + 24206^2 .

It is a cyclic number.

It is not a de Polignac number, because 1005565661 - 2⁶ = 1005565597 is a prime.

It is a super-2 number, since 2×1005565661² = 2022324597164733842, 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 (1005565361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9486416 + ... + 9486521.

It is an arithmetic number, because the mean of its divisors is an integer number (256134663).

Almost surely, 2^1005565661 is an apocalyptic number.

It is an amenable number.

1005565661 is a deficient number, since it is larger than the sum of its proper divisors (18972991).

1005565661 is an equidigital number, since it uses as much as digits as its factorization.

1005565661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18972990.

The product of its (nonzero) digits is 27000, while the sum is 35.

The square root of 1005565661 is about 31710.6553227775. The cubic root of 1005565661 is about 1001.8517890938.

The spelling of 1005565661 in words is "one billion, five million, five hundred sixty-five thousand, six hundred sixty-one".