681881 has 6 divisors (see below), whose sum is σ = 713370. Its totient is φ = 651728.

The previous prime is 681841. The next prime is 681883. The reversal of 681881 is 188186.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 648025 + 33856 = 805^2 + 184^2 .

It is not a de Polignac number, because 681881 - 2¹⁰ = 680857 is a prime.

It is a super-2 number, since 2×681881² = 929923396322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681883) 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 5 ways as a sum of consecutive naturals, for example, 116 + ... + 1173.

It is an arithmetic number, because the mean of its divisors is an integer number (118895).

2⁶⁸¹⁸⁸¹ is an apocalyptic number.

It is an amenable number.

681881 is a deficient number, since it is larger than the sum of its proper divisors (31489).

681881 is a wasteful number, since it uses less digits than its factorization.

681881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1335 (or 1312 counting only the distinct ones).

The product of its digits is 3072, while the sum is 32.

The square root of 681881 is about 825.7608612667. The cubic root of 681881 is about 88.0176015067.

The spelling of 681881 in words is "six hundred eighty-one thousand, eight hundred eighty-one".