20100109 has 4 divisors (see below), whose sum is σ = 20109600. Its totient is φ = 20090620.

The previous prime is 20100097. The next prime is 20100149. The reversal of 20100109 is 90100102.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20100109 - 2¹¹ = 20098061 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20100149) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 42 + ... + 6340.

It is an arithmetic number, because the mean of its divisors is an integer number (5027400).

Almost surely, 2^20100109 is an apocalyptic number.

It is an amenable number.

20100109 is a deficient number, since it is larger than the sum of its proper divisors (9491).

20100109 is an equidigital number, since it uses as much as digits as its factorization.

20100109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9490.

The product of its (nonzero) digits is 18, while the sum is 13.

The square root of 20100109 is about 4483.3145104933. The cubic root of 20100109 is about 271.8939041596.

The spelling of 20100109 in words is "twenty million, one hundred thousand, one hundred nine".