20805005 has 16 divisors (see below), whose sum is σ = 26995584. Its totient is φ = 15301440.

The previous prime is 20804983. The next prime is 20805011. The reversal of 20805005 is 50050802.

It is not a de Polignac number, because 20805005 - 2²⁴ = 4027789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21032 + ... + 21998.

It is an arithmetic number, because the mean of its divisors is an integer number (1687224).

Almost surely, 2^20805005 is an apocalyptic number.

It is an amenable number.

20805005 is a deficient number, since it is larger than the sum of its proper divisors (6190579).

20805005 is a wasteful number, since it uses less digits than its factorization.

20805005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1316.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 20805005 is about 4561.2503768156. The cubic root of 20805005 is about 275.0358300422.

Adding to 20805005 its reverse (50050802), we get a palindrome (70855807).

The spelling of 20805005 in words is "twenty million, eight hundred five thousand, five".