681820 has 24 divisors (see below), whose sum is σ = 1454544. Its totient is φ = 268416.

The previous prime is 681809. The next prime is 681823. The reversal of 681820 is 28186.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681823) 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 7 ways as a sum of consecutive naturals, for example, 1227 + ... + 1693.

It is an arithmetic number, because the mean of its divisors is an integer number (60606).

2⁶⁸¹⁸²⁰ is an apocalyptic number.

It is an amenable number.

681820 is an abundant number, since it is smaller than the sum of its proper divisors (772724).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

681820 is a wasteful number, since it uses less digits than its factorization.

681820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 549 (or 547 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 681820 is about 825.7239248078. The cubic root of 681820 is about 88.0149767898.

The spelling of 681820 in words is "six hundred eighty-one thousand, eight hundred twenty".