661095865 has 8 divisors (see below), whose sum is σ = 798640200. Its totient is φ = 525326592.

The previous prime is 661095859. The next prime is 661095887. The reversal of 661095865 is 568590166.

It can be written as a sum of positive squares in 4 ways, for example, as 69438889 + 591656976 = 8333^2 + 24324^2 .

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 661095865 - 2⁹ = 661095353 is a prime.

It is an unprimeable number.

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, 442944 + ... + 444433.

It is an arithmetic number, because the mean of its divisors is an integer number (99830025).

Almost surely, 2^661095865 is an apocalyptic number.

It is an amenable number.

661095865 is a deficient number, since it is larger than the sum of its proper divisors (137544335).

661095865 is a wasteful number, since it uses less digits than its factorization.

661095865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 887531.

The product of its (nonzero) digits is 388800, while the sum is 46.

The square root of 661095865 is about 25711.7845549468. The cubic root of 661095865 is about 871.1403837042.

The spelling of 661095865 in words is "six hundred sixty-one million, ninety-five thousand, eight hundred sixty-five".