20808765 has 32 divisors (see below), whose sum is σ = 39173760. Its totient is φ = 10444032.

The previous prime is 20808761. The next prime is 20808779. The reversal of 20808765 is 56780802.

It is not a de Polignac number, because 20808765 - 2² = 20808761 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20808761) 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 31 ways as a sum of consecutive naturals, for example, 2239 + ... + 6828.

It is an arithmetic number, because the mean of its divisors is an integer number (1224180).

Almost surely, 2^20808765 is an apocalyptic number.

It is an amenable number.

20808765 is a deficient number, since it is larger than the sum of its proper divisors (18364995).

20808765 is a wasteful number, since it uses less digits than its factorization.

20808765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9098 (or 9092 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The square root of 20808765 is about 4561.6625258780. The cubic root of 20808765 is about 275.0523977291.

The spelling of 20808765 in words is "twenty million, eight hundred eight thousand, seven hundred sixty-five".