646565391 has 12 divisors (see below), whose sum is σ = 951549768. Its totient is φ = 422910384.

The previous prime is 646565389. The next prime is 646565399. The reversal of 646565391 is 193565646.

646565391 is a `hidden beast` number, since 64 + 6 + 56 + 539 + 1 = 666.

646565391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 646565391 - 2¹ = 646565389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646565399) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 677265 + ... + 678218.

It is an arithmetic number, because the mean of its divisors is an integer number (79295814).

Almost surely, 2^646565391 is an apocalyptic number.

646565391 is a deficient number, since it is larger than the sum of its proper divisors (304984377).

646565391 is a wasteful number, since it uses less digits than its factorization.

646565391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1355542 (or 1355539 counting only the distinct ones).

The product of its digits is 583200, while the sum is 45.

The square root of 646565391 is about 25427.6501273712. The cubic root of 646565391 is about 864.7106702718.

The spelling of 646565391 in words is "six hundred forty-six million, five hundred sixty-five thousand, three hundred ninety-one".