221000861 has 2 divisors, whose sum is σ = 221000862. Its totient is φ = 221000860.

The previous prime is 221000839. The next prime is 221000869. The reversal of 221000861 is 168000122.

221000861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 146264836 + 74736025 = 12094^2 + 8645^2 .

It is a cyclic number.

It is not a de Polignac number, because 221000861 - 2⁶ = 221000797 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221000869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110500430 + 110500431.

It is an arithmetic number, because the mean of its divisors is an integer number (110500431).

Almost surely, 2^221000861 is an apocalyptic number.

It is an amenable number.

221000861 is a deficient number, since it is larger than the sum of its proper divisors (1).

221000861 is an equidigital number, since it uses as much as digits as its factorization.

221000861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 221000861 is about 14866.0977058541. The cubic root of 221000861 is about 604.5951447522.

Adding to 221000861 its reverse (168000122), we get a palindrome (389000983).

The spelling of 221000861 in words is "two hundred twenty-one million, eight hundred sixty-one", and thus it is an aban number.