1011561665 has 4 divisors (see below), whose sum is σ = 1213874004. Its totient is φ = 809249328.

The previous prime is 1011561631. The next prime is 1011561701. The reversal of 1011561665 is 5661651101.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5661651101 = 43223 ⋅130987.

It can be written as a sum of positive squares in 2 ways, for example, as 379743169 + 631818496 = 19487^2 + 25136^2 .

It is a cyclic number.

It is not a de Polignac number, because 1011561665 - 2⁶ = 1011561601 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101156162 + ... + 101156171.

It is an arithmetic number, because the mean of its divisors is an integer number (303468501).

Almost surely, 2^1011561665 is an apocalyptic number.

It is an amenable number.

1011561665 is a deficient number, since it is larger than the sum of its proper divisors (202312339).

1011561665 is an equidigital number, since it uses as much as digits as its factorization.

1011561665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202312338.

The product of its (nonzero) digits is 5400, while the sum is 32.

The square root of 1011561665 is about 31805.0572236555. The cubic root of 1011561665 is about 1003.8391305484.

The spelling of 1011561665 in words is "one billion, eleven million, five hundred sixty-one thousand, six hundred sixty-five".