661303165 has 4 divisors (see below), whose sum is σ = 793563804. Its totient is φ = 529042528.

The previous prime is 661303127. The next prime is 661303169. The reversal of 661303165 is 561303166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 467035321 + 194267844 = 21611^2 + 13938^2 .

It is a cyclic number.

It is not a de Polignac number, because 661303165 - 2¹¹ = 661301117 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661303169) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66130312 + ... + 66130321.

It is an arithmetic number, because the mean of its divisors is an integer number (198390951).

Almost surely, 2^661303165 is an apocalyptic number.

It is an amenable number.

661303165 is a deficient number, since it is larger than the sum of its proper divisors (132260639).

661303165 is a wasteful number, since it uses less digits than its factorization.

661303165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132260638.

The product of its (nonzero) digits is 9720, while the sum is 31.

The square root of 661303165 is about 25715.8154644180. The cubic root of 661303165 is about 871.2314287598.

Subtracting from 661303165 its reverse (561303166), we obtain a palindrome (99999999).

The spelling of 661303165 in words is "six hundred sixty-one million, three hundred three thousand, one hundred sixty-five".