221801 has 4 divisors (see below), whose sum is σ = 222852. Its totient is φ = 220752.

The previous prime is 221797. The next prime is 221807. The reversal of 221801 is 108122.

221801 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 179776 + 42025 = 424^2 + 205^2 .

It is a cyclic number.

It is not a de Polignac number, because 221801 - 2² = 221797 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 15.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221801.

It is not an unprimeable number, because it can be changed into a prime (221807) 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, 86 + ... + 671.

It is an arithmetic number, because the mean of its divisors is an integer number (55713).

2²²¹⁸⁰¹ is an apocalyptic number.

It is an amenable number.

221801 is a deficient number, since it is larger than the sum of its proper divisors (1051).

221801 is an equidigital number, since it uses as much as digits as its factorization.

221801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1050.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 221801 is about 470.9575352407. The cubic root of 221801 is about 60.5323916429.

Adding to 221801 its reverse (108122), we get a palindrome (329923).

The spelling of 221801 in words is "two hundred twenty-one thousand, eight hundred one".