20505765 has 48 divisors (see below), whose sum is σ = 39858048. Its totient is φ = 8959104.

The previous prime is 20505761. The next prime is 20505799. The reversal of 20505765 is 56750502.

It is not a de Polignac number, because 20505765 - 2² = 20505761 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20505761) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 16299 + ... + 17511.

It is an arithmetic number, because the mean of its divisors is an integer number (830376).

Almost surely, 2^20505765 is an apocalyptic number.

It is an amenable number.

20505765 is a deficient number, since it is larger than the sum of its proper divisors (19352283).

20505765 is a wasteful number, since it uses less digits than its factorization.

20505765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1258 (or 1251 counting only the distinct ones).

The product of its (nonzero) digits is 10500, while the sum is 30.

The square root of 20505765 is about 4528.3291620641. The cubic root of 20505765 is about 273.7108365400.

The spelling of 20505765 in words is "twenty million, five hundred five thousand, seven hundred sixty-five".