646565123 has 4 divisors (see below), whose sum is σ = 650137488. Its totient is φ = 642992760.

The previous prime is 646565111. The next prime is 646565137. The reversal of 646565123 is 321565646.

It is a happy number.

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 646565123 - 2⁴ = 646565107 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646565173) 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 3 ways as a sum of consecutive naturals, for example, 1785911 + ... + 1786272.

It is an arithmetic number, because the mean of its divisors is an integer number (162534372).

Almost surely, 2^646565123 is an apocalyptic number.

646565123 is a deficient number, since it is larger than the sum of its proper divisors (3572365).

646565123 is a wasteful number, since it uses less digits than its factorization.

646565123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3572364.

The product of its digits is 129600, while the sum is 38.

The square root of 646565123 is about 25427.6448575168. The cubic root of 646565123 is about 864.7105507982.

The spelling of 646565123 in words is "six hundred forty-six million, five hundred sixty-five thousand, one hundred twenty-three".