221951 has 2 divisors, whose sum is σ = 221952. Its totient is φ = 221950.

The previous prime is 221941. The next prime is 221953. The reversal of 221951 is 159122.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221951 is a prime.

Together with 221953, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221953) 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, 110975 + 110976.

It is an arithmetic number, because the mean of its divisors is an integer number (110976).

2²²¹⁹⁵¹ is an apocalyptic number.

221951 is a deficient number, since it is larger than the sum of its proper divisors (1).

221951 is an equidigital number, since it uses as much as digits as its factorization.

221951 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 180, while the sum is 20.

The square root of 221951 is about 471.1167583519. The cubic root of 221951 is about 60.5460342214.

The spelling of 221951 in words is "two hundred twenty-one thousand, nine hundred fifty-one".