665121263 has 4 divisors (see below), whose sum is σ = 665464128. Its totient is φ = 664778400.

The previous prime is 665121257. The next prime is 665121283. The reversal of 665121263 is 362121566.

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

It is a cyclic number.

It is not a de Polignac number, because 665121263 - 2²⁰ = 664072687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665121203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 168506 + ... + 172407.

It is an arithmetic number, because the mean of its divisors is an integer number (166366032).

Almost surely, 2^665121263 is an apocalyptic number.

665121263 is a deficient number, since it is larger than the sum of its proper divisors (342865).

665121263 is a wasteful number, since it uses less digits than its factorization.

665121263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342864.

The product of its digits is 12960, while the sum is 32.

The square root of 665121263 is about 25789.9449980026. The cubic root of 665121263 is about 872.9049252498.

The spelling of 665121263 in words is "six hundred sixty-five million, one hundred twenty-one thousand, two hundred sixty-three".