20806305 has 16 divisors (see below), whose sum is σ = 35851200. Its totient is φ = 10243008.

The previous prime is 20806277. The next prime is 20806339. The reversal of 20806305 is 50360802.

It is not a de Polignac number, because 20806305 - 2¹¹ = 20804257 is a prime.

It is a Curzon 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, 53155 + ... + 53544.

It is an arithmetic number, because the mean of its divisors is an integer number (2240700).

Almost surely, 2^20806305 is an apocalyptic number.

It is an amenable number.

20806305 is a deficient number, since it is larger than the sum of its proper divisors (15044895).

20806305 is a wasteful number, since it uses less digits than its factorization.

20806305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106720.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 20806305 is about 4561.3928793736. The cubic root of 20806305 is about 275.0415584576.

It can be divided in two parts, 2080 and 6305, that added together give a triangular number (8385 = T₁₂₉).

The spelling of 20806305 in words is "twenty million, eight hundred six thousand, three hundred five".