681698 has 4 divisors (see below), whose sum is σ = 1022550. Its totient is φ = 340848.

The previous prime is 681689. The next prime is 681719. The reversal of 681698 is 896186.

681698 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 896186 = 2 ⋅448093.

It can be written as a sum of positive squares in only one way, i.e., 494209 + 187489 = 703^2 + 433^2 .

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 681698.

It is an unprimeable number.

681698 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 170423 + ... + 170426.

2⁶⁸¹⁶⁹⁸ is an apocalyptic number.

681698 is a deficient number, since it is larger than the sum of its proper divisors (340852).

681698 is a wasteful number, since it uses less digits than its factorization.

681698 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340851.

The product of its digits is 20736, while the sum is 38.

The square root of 681698 is about 825.6500469327. The cubic root of 681698 is about 88.0097268863.

The spelling of 681698 in words is "six hundred eighty-one thousand, six hundred ninety-eight".