20205761 has 4 divisors (see below), whose sum is σ = 20222400. Its totient is φ = 20189124.

The previous prime is 20205739. The next prime is 20205767. The reversal of 20205761 is 16750202.

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.

It is a cyclic number.

It is not a de Polignac number, because 20205761 - 2⁶ = 20205697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20205767) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6341 + ... + 8978.

It is an arithmetic number, because the mean of its divisors is an integer number (5055600).

Almost surely, 2^20205761 is an apocalyptic number.

It is an amenable number.

20205761 is a deficient number, since it is larger than the sum of its proper divisors (16639).

20205761 is a wasteful number, since it uses less digits than its factorization.

20205761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16638.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 20205761 is about 4495.0818679975. The cubic root of 20205761 is about 272.3694563114.

Adding to 20205761 its reverse (16750202), we get a palindrome (36955963).

The spelling of 20205761 in words is "twenty million, two hundred five thousand, seven hundred sixty-one".