661660259 has 16 divisors (see below), whose sum is σ = 738276000. Its totient is φ = 588784896.

The previous prime is 661660253. The next prime is 661660261. The reversal of 661660259 is 952066166.

It is a cyclic number.

It is not a de Polignac number, because 661660259 - 2⁴ = 661660243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661660253) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 388592 + ... + 390290.

It is an arithmetic number, because the mean of its divisors is an integer number (46142250).

Almost surely, 2^661660259 is an apocalyptic number.

661660259 is a deficient number, since it is larger than the sum of its proper divisors (76615741).

661660259 is a wasteful number, since it uses less digits than its factorization.

661660259 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2774.

The product of its (nonzero) digits is 116640, while the sum is 41.

The square root of 661660259 is about 25722.7576087790. The cubic root of 661660259 is about 871.3882179353.

The spelling of 661660259 in words is "six hundred sixty-one million, six hundred sixty thousand, two hundred fifty-nine".