20390 has 8 divisors (see below), whose sum is σ = 36720. Its totient is φ = 8152.

The previous prime is 20389. The next prime is 20393. The reversal of 20390 is 9302.

It is a happy number.

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

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20393) 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, 1010 + ... + 1029.

It is an arithmetic number, because the mean of its divisors is an integer number (4590).

2²⁰³⁹⁰ is an apocalyptic number.

20390 is a deficient number, since it is larger than the sum of its proper divisors (16330).

20390 is a wasteful number, since it uses less digits than its factorization.

20390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2046.

The product of its (nonzero) digits is 54, while the sum is 14.

The square root of 20390 is about 142.7935572776. The cubic root of 20390 is about 27.3194787345.

Adding to 20390 its reverse (9302), we get a palindrome (29692).

The spelling of 20390 in words is "twenty thousand, three hundred ninety".