221981939 has 2 divisors, whose sum is σ = 221981940. Its totient is φ = 221981938.

The previous prime is 221981927. The next prime is 221981957. The reversal of 221981939 is 939189122.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221981939 - 2¹² = 221977843 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221981939.

It is not a weakly prime, because it can be changed into another prime (221981909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110990969 + 110990970.

It is an arithmetic number, because the mean of its divisors is an integer number (110990970).

Almost surely, 2^221981939 is an apocalyptic number.

221981939 is a deficient number, since it is larger than the sum of its proper divisors (1).

221981939 is an equidigital number, since it uses as much as digits as its factorization.

221981939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69984, while the sum is 44.

The square root of 221981939 is about 14899.0583259480. The cubic root of 221981939 is about 605.4884737495.

The spelling of 221981939 in words is "two hundred twenty-one million, nine hundred eighty-one thousand, nine hundred thirty-nine".