646865 has 8 divisors (see below), whose sum is σ = 791208. Its totient is φ = 507520.

The previous prime is 646859. The next prime is 646873. The reversal of 646865 is 568646.

It can be written as a sum of positive squares in 4 ways, for example, as 25921 + 620944 = 161^2 + 788^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 646865 - 2⁸ = 646609 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 646865.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 956 + ... + 1485.

It is an arithmetic number, because the mean of its divisors is an integer number (98901).

2⁶⁴⁶⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

646865 is a deficient number, since it is larger than the sum of its proper divisors (144343).

646865 is a wasteful number, since it uses less digits than its factorization.

646865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2499.

The product of its digits is 34560, while the sum is 35.

The square root of 646865 is about 804.2791803845. The cubic root of 646865 is about 86.4844214430.

The spelling of 646865 in words is "six hundred forty-six thousand, eight hundred sixty-five".