681818 has 4 divisors (see below), whose sum is σ = 1022730. Its totient is φ = 340908.

The previous prime is 681809. The next prime is 681823. The reversal of 681818 is 818186.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 677329 + 4489 = 823^2 + 67^2 .

681818 is a modest number, since divided by 1818 gives 68 as remainder.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 170453 + ... + 170456.

2⁶⁸¹⁸¹⁸ is an apocalyptic number.

681818 is a deficient number, since it is larger than the sum of its proper divisors (340912).

681818 is a wasteful number, since it uses less digits than its factorization.

681818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 340911.

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

The square root of 681818 is about 825.7227137484. The cubic root of 681818 is about 88.0148907308.

The spelling of 681818 in words is "six hundred eighty-one thousand, eight hundred eighteen".