665123123 has 16 divisors (see below), whose sum is σ = 768768000. Its totient is φ = 563658912.

The previous prime is 665123119. The next prime is 665123141. The reversal of 665123123 is 321321566.

It is a cyclic number.

It is not a de Polignac number, because 665123123 - 2² = 665123119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (665123923) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 639638 + ... + 640676.

It is an arithmetic number, because the mean of its divisors is an integer number (48048000).

Almost surely, 2^665123123 is an apocalyptic number.

665123123 is a deficient number, since it is larger than the sum of its proper divisors (103644877).

665123123 is a wasteful number, since it uses less digits than its factorization.

665123123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1994.

The product of its digits is 6480, while the sum is 29.

The square root of 665123123 is about 25789.9810585429. The cubic root of 665123123 is about 872.9057389369.

Adding to 665123123 its reverse (321321566), we get a palindrome (986444689).

The spelling of 665123123 in words is "six hundred sixty-five million, one hundred twenty-three thousand, one hundred twenty-three".