691859 has 4 divisors (see below), whose sum is σ = 790704. Its totient is φ = 593016.

The previous prime is 691843. The next prime is 691871. The reversal of 691859 is 958196.

691859 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.

It is a cyclic number.

It is not a de Polignac number, because 691859 - 2⁴ = 691843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691829) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49412 + ... + 49425.

It is an arithmetic number, because the mean of its divisors is an integer number (197676).

2⁶⁹¹⁸⁵⁹ is an apocalyptic number.

691859 is a deficient number, since it is larger than the sum of its proper divisors (98845).

691859 is an equidigital number, since it uses as much as digits as its factorization.

691859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98844.

The product of its digits is 19440, while the sum is 38.

The square root of 691859 is about 831.7806201157. The cubic root of 691859 is about 88.4448463100. Note that the first 3 decimals are identical.

It can be divided in two parts, 69 and 1859, that multiplied together give a triangular number (128271 = T₅₀₆).

The spelling of 691859 in words is "six hundred ninety-one thousand, eight hundred fifty-nine".