684581 has 2 divisors, whose sum is σ = 684582. Its totient is φ = 684580.

The previous prime is 684569. The next prime is 684587. The reversal of 684581 is 185486.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 372100 + 312481 = 610^2 + 559^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-684581 is a prime.

It is a super-2 number, since 2×684581² = 937302291122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (684587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342290 + 342291.

It is an arithmetic number, because the mean of its divisors is an integer number (342291).

2⁶⁸⁴⁵⁸¹ is an apocalyptic number.

It is an amenable number.

684581 is a deficient number, since it is larger than the sum of its proper divisors (1).

684581 is an equidigital number, since it uses as much as digits as its factorization.

684581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7680, while the sum is 32.

The square root of 684581 is about 827.3941019853. The cubic root of 684581 is about 88.1336210401.

The spelling of 684581 in words is "six hundred eighty-four thousand, five hundred eighty-one".