100505 has 4 divisors (see below), whose sum is σ = 120612. Its totient is φ = 80400.

The previous prime is 100501. The next prime is 100511. The reversal of 100505 is 505001.

100505 = T₁₉₈ + T₁₉₉ + ... + T₂₀₂.

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 34969 + 65536 = 187^2 + 256^2 .

It is not a de Polignac number, because 100505 - 2² = 100501 is a prime.

It is a Duffinian number.

100505 is a modest number, since divided by 505 gives 10 as remainder.

It is a Curzon number.

It is a plaindrome in base 14 and base 16.

It is not an unprimeable number, because it can be changed into a prime (100501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10046 + ... + 10055.

It is an arithmetic number, because the mean of its divisors is an integer number (30153).

2¹⁰⁰⁵⁰⁵ is an apocalyptic number.

It is an amenable number.

100505 is a deficient number, since it is larger than the sum of its proper divisors (20107).

100505 is an equidigital number, since it uses as much as digits as its factorization.

100505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20106.

The product of its (nonzero) digits is 25, while the sum is 11.

The square root of 100505 is about 317.0252355886. The cubic root of 100505 is about 46.4938905913.

Adding to 100505 its reverse (505001), we get a palindrome (605506).

Subtracting 100505 from its reverse (505001), we obtain a square (404496 = 636²).

The spelling of 100505 in words is "one hundred thousand, five hundred five".