221987 has 2 divisors, whose sum is σ = 221988. Its totient is φ = 221986.

The previous prime is 221957. The next prime is 221989. The reversal of 221987 is 789122.

It is a happy number.

221987 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 is a cyclic number.

It is not a de Polignac number, because 221987 - 2¹⁴ = 205603 is a prime.

Together with 221989, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110993 + 110994.

It is an arithmetic number, because the mean of its divisors is an integer number (110994).

2²²¹⁹⁸⁷ is an apocalyptic number.

221987 is a deficient number, since it is larger than the sum of its proper divisors (1).

221987 is an equidigital number, since it uses as much as digits as its factorization.

221987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 29.

The square root of 221987 is about 471.1549638919. The cubic root of 221987 is about 60.5493075256.

The spelling of 221987 in words is "two hundred twenty-one thousand, nine hundred eighty-seven".