221581081 has 4 divisors (see below), whose sum is σ = 221916964. Its totient is φ = 221245200.

The previous prime is 221581079. The next prime is 221581093. The reversal of 221581081 is 180185122.

221581081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 107433225 + 114147856 = 10365^2 + 10684^2 .

It is a cyclic number.

It is not a de Polignac number, because 221581081 - 2¹ = 221581079 is a prime.

It is a super-2 number, since 2×221581081² = 98196350914257122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221581001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166950 + ... + 168271.

It is an arithmetic number, because the mean of its divisors is an integer number (55479241).

Almost surely, 2^221581081 is an apocalyptic number.

It is an amenable number.

221581081 is a deficient number, since it is larger than the sum of its proper divisors (335883).

221581081 is an equidigital number, since it uses as much as digits as its factorization.

221581081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335882.

The product of its (nonzero) digits is 1280, while the sum is 28.

The square root of 221581081 is about 14885.5997863707. The cubic root of 221581081 is about 605.1237877068.

The spelling of 221581081 in words is "two hundred twenty-one million, five hundred eighty-one thousand, eighty-one".