221099581 has 2 divisors, whose sum is σ = 221099582. Its totient is φ = 221099580.

The previous prime is 221099579. The next prime is 221099587. The reversal of 221099581 is 185990122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 217297081 + 3802500 = 14741^2 + 1950^2 .

It is a cyclic number.

It is not a de Polignac number, because 221099581 - 2¹ = 221099579 is a prime.

It is a super-2 number, since 2×221099581² = 97770049436751122, which contains 22 as substring.

Together with 221099579, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221099581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221099587) 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, 110549790 + 110549791.

It is an arithmetic number, because the mean of its divisors is an integer number (110549791).

Almost surely, 2^221099581 is an apocalyptic number.

It is an amenable number.

221099581 is a deficient number, since it is larger than the sum of its proper divisors (1).

221099581 is an equidigital number, since it uses as much as digits as its factorization.

221099581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12960, while the sum is 37.

The square root of 221099581 is about 14869.4176415891. The cubic root of 221099581 is about 604.6851545792.

The spelling of 221099581 in words is "two hundred twenty-one million, ninety-nine thousand, five hundred eighty-one".