221939 has 4 divisors (see below), whose sum is σ = 233640. Its totient is φ = 210240.

The previous prime is 221909. The next prime is 221941. The reversal of 221939 is 939122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 939122 = 2 ⋅469561.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221939 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221909) 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 in 3 ways as a sum of consecutive naturals, for example, 5822 + ... + 5859.

It is an arithmetic number, because the mean of its divisors is an integer number (58410).

2²²¹⁹³⁹ is an apocalyptic number.

221939 is a deficient number, since it is larger than the sum of its proper divisors (11701).

221939 is a wasteful number, since it uses less digits than its factorization.

221939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11700.

The product of its digits is 972, while the sum is 26.

The square root of 221939 is about 471.1040224834. The cubic root of 221939 is about 60.5449430414.

The spelling of 221939 in words is "two hundred twenty-one thousand, nine hundred thirty-nine".