647765 has 4 divisors (see below), whose sum is σ = 777324. Its totient is φ = 518208.

The previous prime is 647753. The next prime is 647771. The reversal of 647765 is 567746.

647765 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 567746 = 2 ⋅283873.

It can be written as a sum of positive squares in 2 ways, for example, as 68644 + 579121 = 262^2 + 761^2 .

It is a cyclic number.

It is not a de Polignac number, because 647765 - 2⁸ = 647509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 647765.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64772 + ... + 64781.

It is an arithmetic number, because the mean of its divisors is an integer number (194331).

2⁶⁴⁷⁷⁶⁵ is an apocalyptic number.

It is an amenable number.

647765 is a deficient number, since it is larger than the sum of its proper divisors (129559).

647765 is a wasteful number, since it uses less digits than its factorization.

647765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129558.

The product of its digits is 35280, while the sum is 35.

The square root of 647765 is about 804.8384931152. The cubic root of 647765 is about 86.5245121929.

The spelling of 647765 in words is "six hundred forty-seven thousand, seven hundred sixty-five".