684965 has 4 divisors (see below), whose sum is σ = 821964. Its totient is φ = 547968.

The previous prime is 684961. The next prime is 684973. The reversal of 684965 is 569486.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 569486 = 2 ⋅284743.

It can be written as a sum of positive squares in 2 ways, for example, as 470596 + 214369 = 686^2 + 463^2 .

It is a cyclic number.

It is not a de Polignac number, because 684965 - 2² = 684961 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68492 + ... + 68501.

It is an arithmetic number, because the mean of its divisors is an integer number (205491).

2⁶⁸⁴⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

684965 is a deficient number, since it is larger than the sum of its proper divisors (136999).

684965 is a wasteful number, since it uses less digits than its factorization.

684965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136998.

The product of its digits is 51840, while the sum is 38.

The square root of 684965 is about 827.6261233190. The cubic root of 684965 is about 88.1500968039.

The spelling of 684965 in words is "six hundred eighty-four thousand, nine hundred sixty-five".