20105815 has 16 divisors (see below), whose sum is σ = 26034048. Its totient is φ = 14849536.

The previous prime is 20105807. The next prime is 20105861. The reversal of 20105815 is 51850102.

It is a cyclic number.

It is not a de Polignac number, because 20105815 - 2³ = 20105807 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 2274 + ... + 6736.

It is an arithmetic number, because the mean of its divisors is an integer number (1627128).

Almost surely, 2^20105815 is an apocalyptic number.

20105815 is a deficient number, since it is larger than the sum of its proper divisors (5928233).

20105815 is a wasteful number, since it uses less digits than its factorization.

20105815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4538.

The product of its (nonzero) digits is 400, while the sum is 22.

The square root of 20105815 is about 4483.9508248865. The cubic root of 20105815 is about 271.9196300538.

Adding to 20105815 its reverse (51850102), we get a palindrome (71955917).

The spelling of 20105815 in words is "twenty million, one hundred five thousand, eight hundred fifteen".