20809775 has 12 divisors (see below), whose sum is σ = 29490672. Its totient is φ = 14269440.

The previous prime is 20809759. The next prime is 20809777. The reversal of 20809775 is 57790802.

It is not a de Polignac number, because 20809775 - 2⁴ = 20809759 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20809777) 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 11 ways as a sum of consecutive naturals, for example, 59282 + ... + 59631.

It is an arithmetic number, because the mean of its divisors is an integer number (2457556).

Almost surely, 2^20809775 is an apocalyptic number.

20809775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

20809775 is a deficient number, since it is larger than the sum of its proper divisors (8680897).

20809775 is a wasteful number, since it uses less digits than its factorization.

20809775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118930 (or 118925 counting only the distinct ones).

The product of its (nonzero) digits is 35280, while the sum is 38.

The square root of 20809775 is about 4561.7732297869. The cubic root of 20809775 is about 275.0568477518.

The spelling of 20809775 in words is "twenty million, eight hundred nine thousand, seven hundred seventy-five".