20663 has 2 divisors, whose sum is σ = 20664. Its totient is φ = 20662.

The previous prime is 20641. The next prime is 20681. The reversal of 20663 is 36602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20663 - 2⁶ = 20599 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10331 + 10332.

It is an arithmetic number, because the mean of its divisors is an integer number (10332).

2²⁰⁶⁶³ is an apocalyptic number.

20663 is a deficient number, since it is larger than the sum of its proper divisors (1).

20663 is an equidigital number, since it uses as much as digits as its factorization.

20663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 17.

The square root of 20663 is about 143.7463043003. The cubic root of 20663 is about 27.4408646635.

The spelling of 20663 in words is "twenty thousand, six hundred sixty-three".