661665505 has 8 divisors (see below), whose sum is σ = 794245824. Its totient is φ = 529167600.

The previous prime is 661665497. The next prime is 661665509. The reversal of 661665505 is 505566166.

661665505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 661665505 - 2³ = 661665497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661665509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1291 + ... + 36400.

It is an arithmetic number, because the mean of its divisors is an integer number (99280728).

Almost surely, 2^661665505 is an apocalyptic number.

It is an amenable number.

661665505 is a deficient number, since it is larger than the sum of its proper divisors (132580319).

661665505 is a wasteful number, since it uses less digits than its factorization.

661665505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41207.

The product of its (nonzero) digits is 162000, while the sum is 40.

The square root of 661665505 is about 25722.8595805365. The cubic root of 661665505 is about 871.3905208747.

The spelling of 661665505 in words is "six hundred sixty-one million, six hundred sixty-five thousand, five hundred five".