221742181 has 2 divisors, whose sum is σ = 221742182. Its totient is φ = 221742180.

The previous prime is 221742161. The next prime is 221742187. The reversal of 221742181 is 181247122.

221742181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155401156 + 66341025 = 12466^2 + 8145^2 .

It is a cyclic number.

It is not a de Polignac number, because 221742181 - 2¹³ = 221733989 is a prime.

It is a super-2 number, since 2×221742181² = 98339189669273522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221742187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110871090 + 110871091.

It is an arithmetic number, because the mean of its divisors is an integer number (110871091).

Almost surely, 2^221742181 is an apocalyptic number.

It is an amenable number.

221742181 is a deficient number, since it is larger than the sum of its proper divisors (1).

221742181 is an equidigital number, since it uses as much as digits as its factorization.

221742181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1792, while the sum is 28.

The square root of 221742181 is about 14891.0100731952. The cubic root of 221742181 is about 605.2704034524.

The spelling of 221742181 in words is "two hundred twenty-one million, seven hundred forty-two thousand, one hundred eighty-one".