20965 has 8 divisors (see below), whose sum is σ = 28800. Its totient is φ = 14352.

The previous prime is 20963. The next prime is 20981. The reversal of 20965 is 56902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20965 - 2¹ = 20963 is a prime.

20965 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20963) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 265 + ... + 334.

It is an arithmetic number, because the mean of its divisors is an integer number (3600).

2²⁰⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

20965 is a deficient number, since it is larger than the sum of its proper divisors (7835).

20965 is an equidigital number, since it uses as much as digits as its factorization.

20965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 611.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 20965 is about 144.7929556298. The cubic root of 20965 is about 27.5739058842.

Subtracting 20965 from its reverse (56902), we obtain a cube (35937 = 33³).

The spelling of 20965 in words is "twenty thousand, nine hundred sixty-five".