20668 has 6 divisors (see below), whose sum is σ = 36176. Its totient is φ = 10332.

The previous prime is 20663. The next prime is 20681. The reversal of 20668 is 86602.

It is a plaindrome in base 11.

It is a nialpdrome in base 12 and base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2580 + ... + 2587.

2²⁰⁶⁶⁸ is an apocalyptic number.

It is an amenable number.

20668 is a deficient number, since it is larger than the sum of its proper divisors (15508).

20668 is a wasteful number, since it uses less digits than its factorization.

20668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5171 (or 5169 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 20668 is about 143.7636949998. The cubic root of 20668 is about 27.4430778506.

The spelling of 20668 in words is "twenty thousand, six hundred sixty-eight".