221938081 has 2 divisors, whose sum is σ = 221938082. Its totient is φ = 221938080.

The previous prime is 221938051. The next prime is 221938091. The reversal of 221938081 is 180839122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 208542481 + 13395600 = 14441^2 + 3660^2 .

It is a cyclic number.

It is not a de Polignac number, because 221938081 - 2⁷ = 221937953 is a prime.

It is a super-2 number, since 2×221938081² = 98513023595925122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (221938001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110969040 + 110969041.

It is an arithmetic number, because the mean of its divisors is an integer number (110969041).

Almost surely, 2^221938081 is an apocalyptic number.

It is an amenable number.

221938081 is a deficient number, since it is larger than the sum of its proper divisors (1).

221938081 is an equidigital number, since it uses as much as digits as its factorization.

221938081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 221938081 is about 14897.5864152553. The cubic root of 221938081 is about 605.4485947355.

The spelling of 221938081 in words is "two hundred twenty-one million, nine hundred thirty-eight thousand, eighty-one".