20205705 has 16 divisors (see below), whose sum is σ = 34816320. Its totient is φ = 9947328.

The previous prime is 20205697. The next prime is 20205709. The reversal of 20205705 is 50750202.

It is not a de Polignac number, because 20205705 - 2³ = 20205697 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20205709) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51615 + ... + 52004.

It is an arithmetic number, because the mean of its divisors is an integer number (2176020).

Almost surely, 2^20205705 is an apocalyptic number.

It is an amenable number.

20205705 is a deficient number, since it is larger than the sum of its proper divisors (14610615).

20205705 is a wasteful number, since it uses less digits than its factorization.

20205705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103640.

The product of its (nonzero) digits is 700, while the sum is 21.

The square root of 20205705 is about 4495.0756389632. The cubic root of 20205705 is about 272.3692046884.

Adding to 20205705 its reverse (50750202), we get a palindrome (70955907).

It can be divided in two parts, 20205 and 705, that added together give a triangular number (20910 = T₂₀₄).

The spelling of 20205705 in words is "twenty million, two hundred five thousand, seven hundred five".