19801 has 2 divisors, whose sum is σ = 19802. Its totient is φ = 19800.

The previous prime is 19793. The next prime is 19813. The reversal of 19801 is 10891.

19801 = 99² + 100².

19801 is nontrivially palindromic in base 2.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10000 + 9801 = 100^2 + 99^2 .

It is an emirp because it is prime and its reverse (10891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19801 - 2³ = 19793 is a prime.

It is not a weakly prime, because it can be changed into another prime (19841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9900 + 9901.

It is an arithmetic number, because the mean of its divisors is an integer number (9901).

2¹⁹⁸⁰¹ is an apocalyptic number.

19801 is the 100-th centered square number.

It is an amenable number.

19801 is a deficient number, since it is larger than the sum of its proper divisors (1).

19801 is an equidigital number, since it uses as much as digits as its factorization.

19801 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 19.

The square root of 19801 is about 140.7160260951. The cubic root of 19801 is about 27.0538477266.

It can be divided in two parts, 19 and 801, that added together give a triangular number (820 = T₄₀).

The spelling of 19801 in words is "nineteen thousand, eight hundred one".