684981 has 36 divisors (see below), whose sum is σ = 1182636. Its totient is φ = 380160.

The previous prime is 684977. The next prime is 684989. The reversal of 684981 is 189486.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 576081 + 108900 = 759^2 + 330^2 .

It is not a de Polignac number, because 684981 - 2² = 684977 is a prime.

It is a super-2 number, since 2×684981² = 938397940722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684989) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 18495 + ... + 18531.

It is an arithmetic number, because the mean of its divisors is an integer number (32851).

2⁶⁸⁴⁹⁸¹ is an apocalyptic number.

It is an amenable number.

684981 is a deficient number, since it is larger than the sum of its proper divisors (497655).

684981 is a wasteful number, since it uses less digits than its factorization.

684981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82 (or 68 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The square root of 684981 is about 827.6357894630. The cubic root of 684981 is about 88.1507831605.

The spelling of 684981 in words is "six hundred eighty-four thousand, nine hundred eighty-one".