20487 has 4 divisors (see below), whose sum is σ = 27320. Its totient is φ = 13656.

The previous prime is 20483. The next prime is 20507. The reversal of 20487 is 78402.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 20487 - 2² = 20483 is a prime.

It is a D-number.

It is a Duffinian number.

20487 is a lucky number.

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 (20483) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3412 + ... + 3417.

It is an arithmetic number, because the mean of its divisors is an integer number (6830).

2²⁰⁴⁸⁷ is an apocalyptic number.

20487 is a deficient number, since it is larger than the sum of its proper divisors (6833).

20487 is an equidigital number, since it uses as much as digits as its factorization.

20487 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6832.

The product of its (nonzero) digits is 448, while the sum is 21.

The square root of 20487 is about 143.1328054640. The cubic root of 20487 is about 27.3627319354.

Adding to 20487 its reverse (78402), we get a palindrome (98889).

The spelling of 20487 in words is "twenty thousand, four hundred eighty-seven".