221312081 has 2 divisors, whose sum is σ = 221312082. Its totient is φ = 221312080.

The previous prime is 221312053. The next prime is 221312149. The reversal of 221312081 is 180213122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 204633025 + 16679056 = 14305^2 + 4084^2 .

It is a cyclic number.

It is not a de Polignac number, because 221312081 - 2¹⁸ = 221049937 is a prime.

It is a super-2 number, since 2×221312081² = 97958074393101122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221312011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110656040 + 110656041.

It is an arithmetic number, because the mean of its divisors is an integer number (110656041).

Almost surely, 2^221312081 is an apocalyptic number.

It is an amenable number.

221312081 is a deficient number, since it is larger than the sum of its proper divisors (1).

221312081 is an equidigital number, since it uses as much as digits as its factorization.

221312081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 221312081 is about 14876.5614642632. The cubic root of 221312081 is about 604.8788146045.

The spelling of 221312081 in words is "two hundred twenty-one million, three hundred twelve thousand, eighty-one".