100805 has 4 divisors (see below), whose sum is σ = 120972. Its totient is φ = 80640.

The previous prime is 100801. The next prime is 100811. The reversal of 100805 is 508001.

100805 is nontrivially palindromic in base 13.

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

It can be written as a sum of positive squares in 2 ways, for example, as 51076 + 49729 = 226^2 + 223^2 .

It is not a de Polignac number, because 100805 - 2² = 100801 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 100805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100801) 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, 10076 + ... + 10085.

It is an arithmetic number, because the mean of its divisors is an integer number (30243).

2¹⁰⁰⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

100805 is a deficient number, since it is larger than the sum of its proper divisors (20167).

100805 is an equidigital number, since it uses as much as digits as its factorization.

100805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20166.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 100805 is about 317.4980314900. The cubic root of 100805 is about 46.5401049159.

Adding to 100805 its reverse (508001), we get a palindrome (608806).

The spelling of 100805 in words is "one hundred thousand, eight hundred five".