20669 has 4 divisors (see below), whose sum is σ = 22560. Its totient is φ = 18780.

The previous prime is 20663. The next prime is 20681. The reversal of 20669 is 96602.

20669 = 82² + 83² + 84².

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 20669 - 2¹² = 16573 is a prime.

It is a super-2 number, since 2×20669² = 854415122, which contains 22 as substring.

It is a Duffinian number.

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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 929 + ... + 950.

It is an arithmetic number, because the mean of its divisors is an integer number (5640).

2²⁰⁶⁶⁹ is an apocalyptic number.

It is an amenable number.

20669 is a deficient number, since it is larger than the sum of its proper divisors (1891).

20669 is a wasteful number, since it uses less digits than its factorization.

20669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1890.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 20669 is about 143.7671728873. The cubic root of 20669 is about 27.4435204452.

The spelling of 20669 in words is "twenty thousand, six hundred sixty-nine".