221165993 has 2 divisors, whose sum is σ = 221165994. Its totient is φ = 221165992.

The previous prime is 221165981. The next prime is 221166007. The reversal of 221165993 is 399561122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 168922009 + 52243984 = 12997^2 + 7228^2 .

It is a cyclic number.

It is not a de Polignac number, because 221165993 - 2⁶ = 221165929 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (221165933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110582996 + 110582997.

It is an arithmetic number, because the mean of its divisors is an integer number (110582997).

Almost surely, 2^221165993 is an apocalyptic number.

It is an amenable number.

221165993 is a deficient number, since it is larger than the sum of its proper divisors (1).

221165993 is an equidigital number, since it uses as much as digits as its factorization.

221165993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 29160, while the sum is 38.

The square root of 221165993 is about 14871.6506481291. The cubic root of 221165993 is about 604.7456919023.

The spelling of 221165993 in words is "two hundred twenty-one million, one hundred sixty-five thousand, nine hundred ninety-three".