20105905 has 8 divisors (see below), whose sum is σ = 24522984. Its totient is φ = 15820800.

The previous prime is 20105873. The next prime is 20105927. The reversal of 20105905 is 50950102.

It can be written as a sum of positive squares in 4 ways, for example, as 1382976 + 18722929 = 1176^2 + 4327^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20105905 - 2⁵ = 20105873 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32656 + ... + 33265.

It is an arithmetic number, because the mean of its divisors is an integer number (3065373).

Almost surely, 2^20105905 is an apocalyptic number.

It is an amenable number.

20105905 is a deficient number, since it is larger than the sum of its proper divisors (4417079).

20105905 is an equidigital number, since it uses as much as digits as its factorization.

20105905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65987.

The product of its (nonzero) digits is 450, while the sum is 22.

The square root of 20105905 is about 4483.9608606677. The cubic root of 20105905 is about 271.9200357860.

The spelling of 20105905 in words is "twenty million, one hundred five thousand, nine hundred five".