685261 has 4 divisors (see below), whose sum is σ = 690624. Its totient is φ = 679900.

The previous prime is 685249. The next prime is 685271. The reversal of 685261 is 162586.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 162586 = 2 ⋅81293.

It is a cyclic number.

It is not a de Polignac number, because 685261 - 2¹⁵ = 652493 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 (685231) 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, 2485 + ... + 2746.

It is an arithmetic number, because the mean of its divisors is an integer number (172656).

2⁶⁸⁵²⁶¹ is an apocalyptic number.

It is an amenable number.

685261 is a deficient number, since it is larger than the sum of its proper divisors (5363).

685261 is a wasteful number, since it uses less digits than its factorization.

685261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5362.

The product of its digits is 2880, while the sum is 28.

The square root of 685261 is about 827.8049287121. The cubic root of 685261 is about 88.1627926697.

It can be divided in two parts, 685 and 261, that added together give a triangular number (946 = T₄₃).

The spelling of 685261 in words is "six hundred eighty-five thousand, two hundred sixty-one".