1015661665 has 4 divisors (see below), whose sum is σ = 1218794004. Its totient is φ = 812529328.

The previous prime is 1015661653. The next prime is 1015661707. The reversal of 1015661665 is 5661665101.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5661665101 = 389 ⋅14554409.

It can be written as a sum of positive squares in 2 ways, for example, as 401761936 + 613899729 = 20044^2 + 24777^2 .

It is a cyclic number.

It is not a de Polignac number, because 1015661665 - 2²⁵ = 982107233 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 101566162 + ... + 101566171.

It is an arithmetic number, because the mean of its divisors is an integer number (304698501).

Almost surely, 2^1015661665 is an apocalyptic number.

It is an amenable number.

1015661665 is a deficient number, since it is larger than the sum of its proper divisors (203132339).

1015661665 is an equidigital number, since it uses as much as digits as its factorization.

1015661665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203132338.

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 1015661665 is about 31869.4472026108. The cubic root of 1015661665 is about 1005.1935354943.

The spelling of 1015661665 in words is "one billion, fifteen million, six hundred sixty-one thousand, six hundred sixty-five".