19901 has 4 divisors (see below), whose sum is σ = 22752. Its totient is φ = 17052.

The previous prime is 19891. The next prime is 19913. The reversal of 19901 is 10991.

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, and also an emirpimes, since its reverse is a distinct semiprime: 10991 = 29 ⋅379.

It is not a de Polignac number, because 19901 - 2¹⁴ = 3517 is a prime.

It is a pancake number, because a pancake can be divided into 19901 parts by 199 straight cuts.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19961) 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, 1415 + ... + 1428.

It is an arithmetic number, because the mean of its divisors is an integer number (5688).

2¹⁹⁹⁰¹ is an apocalyptic number.

It is an amenable number.

19901 is a deficient number, since it is larger than the sum of its proper divisors (2851).

19901 is an equidigital number, since it uses as much as digits as its factorization.

19901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2850.

The product of its (nonzero) digits is 81, while the sum is 20.

The square root of 19901 is about 141.0709041582. The cubic root of 19901 is about 27.0993141714.

Subtracting from 19901 its sum of digits (20), we obtain a square (19881 = 141²).

It can be divided in two parts, 1990 and 1, that added together give a palindrome (1991).

The spelling of 19901 in words is "nineteen thousand, nine hundred one".