20685761 has 4 divisors (see below), whose sum is σ = 20697024. Its totient is φ = 20674500.

The previous prime is 20685733. The next prime is 20685811. The reversal of 20685761 is 16758602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20685761 - 2⁶ = 20685697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20684761) 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 3 ways as a sum of consecutive naturals, for example, 2165 + ... + 6786.

It is an arithmetic number, because the mean of its divisors is an integer number (5174256).

Almost surely, 2^20685761 is an apocalyptic number.

It is an amenable number.

20685761 is a deficient number, since it is larger than the sum of its proper divisors (11263).

20685761 is an equidigital number, since it uses as much as digits as its factorization.

20685761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11262.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 20685761 is about 4548.1601774784. The cubic root of 20685761 is about 274.5093664929.

The spelling of 20685761 in words is "twenty million, six hundred eighty-five thousand, seven hundred sixty-one".