221011993 has 2 divisors, whose sum is σ = 221011994. Its totient is φ = 221011992.

The previous prime is 221011943. The next prime is 221012039. The reversal of 221011993 is 399110122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 115498009 + 105513984 = 10747^2 + 10272^2 .

It is a cyclic number.

It is not a de Polignac number, because 221011993 - 2⁹ = 221011481 is a prime.

It is not a weakly prime, because it can be changed into another prime (221011913) 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 as a sum of consecutive naturals, namely, 110505996 + 110505997.

It is an arithmetic number, because the mean of its divisors is an integer number (110505997).

Almost surely, 2^221011993 is an apocalyptic number.

It is an amenable number.

221011993 is a deficient number, since it is larger than the sum of its proper divisors (1).

221011993 is an equidigital number, since it uses as much as digits as its factorization.

221011993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 221011993 is about 14866.4721100872. The cubic root of 221011993 is about 604.6052959044.

The spelling of 221011993 in words is "two hundred twenty-one million, eleven thousand, nine hundred ninety-three".