220861 has 2 divisors, whose sum is σ = 220862. Its totient is φ = 220860.

The previous prime is 220859. The next prime is 220873. The reversal of 220861 is 168022.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 219961 + 900 = 469^2 + 30^2 .

It is a cyclic number.

It is not a de Polignac number, because 220861 - 2¹ = 220859 is a prime.

Together with 220859, it forms a pair of twin primes.

220861 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (220811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110430 + 110431.

It is an arithmetic number, because the mean of its divisors is an integer number (110431).

2²²⁰⁸⁶¹ is an apocalyptic number.

It is an amenable number.

220861 is a deficient number, since it is larger than the sum of its proper divisors (1).

220861 is an equidigital number, since it uses as much as digits as its factorization.

220861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 220861 is about 469.9585088069. The cubic root of 220861 is about 60.4467577940.

Adding to 220861 its reverse (168022), we get a palindrome (388883).

It can be divided in two parts, 220 and 861, that multiplied together give a triangular number (189420 = T₆₁₅).

The spelling of 220861 in words is "two hundred twenty thousand, eight hundred sixty-one".