20761 has 4 divisors (see below), whose sum is σ = 22372. Its totient is φ = 19152.

The previous prime is 20759. The next prime is 20771. The reversal of 20761 is 16702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3600 + 17161 = 60^2 + 131^2 .

It is a cyclic number.

It is not a de Polignac number, because 20761 - 2¹ = 20759 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20731) 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, 786 + ... + 811.

It is an arithmetic number, because the mean of its divisors is an integer number (5593).

2²⁰⁷⁶¹ is an apocalyptic number.

It is an amenable number.

20761 is a deficient number, since it is larger than the sum of its proper divisors (1611).

20761 is a wasteful number, since it uses less digits than its factorization.

20761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1610.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 20761 is about 144.0867794074. The cubic root of 20761 is about 27.4841782267.

The spelling of 20761 in words is "twenty thousand, seven hundred sixty-one".