20105899 has 4 divisors (see below), whose sum is σ = 21933720. Its totient is φ = 18278080.

The previous prime is 20105873. The next prime is 20105927. The reversal of 20105899 is 99850102.

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 20105899 - 2⁹ = 20105387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20105399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 913894 + ... + 913915.

It is an arithmetic number, because the mean of its divisors is an integer number (5483430).

Almost surely, 2^20105899 is an apocalyptic number.

20105899 is a deficient number, since it is larger than the sum of its proper divisors (1827821).

20105899 is a wasteful number, since it uses less digits than its factorization.

20105899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1827820.

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 20105899 is about 4483.9601916163. The cubic root of 20105899 is about 271.9200087373.

The spelling of 20105899 in words is "twenty million, one hundred five thousand, eight hundred ninety-nine".