20481 has 4 divisors (see below), whose sum is σ = 27312. Its totient is φ = 13652.

The previous prime is 20479. The next prime is 20483. The reversal of 20481 is 18402.

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 an interprime number because it is at equal distance from previous prime (20479) and next prime (20483).

It is a cyclic number.

It is not a de Polignac number, because 20481 - 2¹ = 20479 is a prime.

It is a super-2 number, since 2×20481² = 838942722, which contains 22 as substring.

It is a D-number.

It is a plaindrome in base 7.

It is a self number, because there is not a number n which added to its sum of digits gives 20481.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 20481.

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 (3) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3411 + ... + 3416.

It is an arithmetic number, because the mean of its divisors is an integer number (6828).

It is a Proth number, since it is equal to 5 ⋅ 2¹² + 1 and 5 < 2¹².

2²⁰⁴⁸¹ is an apocalyptic number.

It is an amenable number.

20481 is a deficient number, since it is larger than the sum of its proper divisors (6831).

20481 is an equidigital number, since it uses as much as digits as its factorization.

20481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6830.

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 20481 is about 143.1118443736. Note that the first 3 decimals coincide. The cubic root of 20481 is about 27.3600604458.

Adding to 20481 its reverse (18402), we get a palindrome (38883).

The spelling of 20481 in words is "twenty thousand, four hundred eighty-one".