647646781565 has 32 divisors (see below), whose sum is σ = 911718823680. Its totient is φ = 432386035200.

The previous prime is 647646781543. The next prime is 647646781567. The reversal of 647646781565 is 565187646746.

It is not a de Polignac number, because 647646781565 - 2⁶ = 647646781501 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (647646781567) 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 31 ways as a sum of consecutive naturals, for example, 244991 + ... + 1164179.

It is an arithmetic number, because the mean of its divisors is an integer number (28491213240).

Almost surely, 2^647646781565 is an apocalyptic number.

It is an amenable number.

647646781565 is a deficient number, since it is larger than the sum of its proper divisors (264072042115).

647646781565 is a wasteful number, since it uses less digits than its factorization.

647646781565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 919733.

The product of its digits is 203212800, while the sum is 65.

The spelling of 647646781565 in words is "six hundred forty-seven billion, six hundred forty-six million, seven hundred eighty-one thousand, five hundred sixty-five".