221807 has 2 divisors, whose sum is σ = 221808. Its totient is φ = 221806.

The previous prime is 221797. The next prime is 221813. The reversal of 221807 is 708122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221807 - 2¹⁰ = 220783 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110903 + 110904.

It is an arithmetic number, because the mean of its divisors is an integer number (110904).

2²²¹⁸⁰⁷ is an apocalyptic number.

221807 is a deficient number, since it is larger than the sum of its proper divisors (1).

221807 is an equidigital number, since it uses as much as digits as its factorization.

221807 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 221807 is about 470.9639051987. The cubic root of 221807 is about 60.5329374641.

Adding to 221807 its reverse (708122), we get a palindrome (929929).

The spelling of 221807 in words is "two hundred twenty-one thousand, eight hundred seven".