20901 has 4 divisors (see below), whose sum is σ = 27872. Its totient is φ = 13932.

The previous prime is 20899. The next prime is 20903. The reversal of 20901 is 10902.

It is a happy number.

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 (20899) and next prime (20903).

It is not a de Polignac number, because 20901 - 2¹ = 20899 is a prime.

It is a D-number.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20903) 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 in 3 ways as a sum of consecutive naturals, for example, 3481 + ... + 3486.

It is an arithmetic number, because the mean of its divisors is an integer number (6968).

2²⁰⁹⁰¹ is an apocalyptic number.

It is an amenable number.

20901 is a deficient number, since it is larger than the sum of its proper divisors (6971).

20901 is an equidigital number, since it uses as much as digits as its factorization.

20901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6970.

The product of its (nonzero) digits is 18, while the sum is 12.

The square root of 20901 is about 144.5717814790. The cubic root of 20901 is about 27.5458189335.

Subtracting from 20901 its reverse (10902), we obtain a palindrome (9999).

The spelling of 20901 in words is "twenty thousand, nine hundred one".