681779 has 4 divisors (see below), whose sum is σ = 779184. Its totient is φ = 584376.

The previous prime is 681773. The next prime is 681781. The reversal of 681779 is 977186.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 681779 - 2⁴ = 681763 is a prime.

It is not an unprimeable number, because it can be changed into a prime (681773) 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, 48692 + ... + 48705.

It is an arithmetic number, because the mean of its divisors is an integer number (194796).

2⁶⁸¹⁷⁷⁹ is an apocalyptic number.

681779 is a deficient number, since it is larger than the sum of its proper divisors (97405).

681779 is an equidigital number, since it uses as much as digits as its factorization.

681779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97404.

The product of its digits is 21168, while the sum is 38.

The square root of 681779 is about 825.6990977348. The cubic root of 681779 is about 88.0132125478.

It can be divided in two parts, 68177 and 9, that added together give a palindrome (68186).

The spelling of 681779 in words is "six hundred eighty-one thousand, seven hundred seventy-nine".