221091097 has 4 divisors (see below), whose sum is σ = 221616676. Its totient is φ = 220565520.

The previous prime is 221091053. The next prime is 221091127. The reversal of 221091097 is 790190122.

221091097 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, and also an emirpimes, since its reverse is a distinct semiprime: 790190122 = 2 ⋅395095061.

It can be written as a sum of positive squares in 2 ways, for example, as 21123216 + 199967881 = 4596^2 + 14141^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221091097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221091197) 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, 262158 + ... + 262999.

It is an arithmetic number, because the mean of its divisors is an integer number (55404169).

Almost surely, 2^221091097 is an apocalyptic number.

It is an amenable number.

221091097 is a deficient number, since it is larger than the sum of its proper divisors (525579).

221091097 is an equidigital number, since it uses as much as digits as its factorization.

221091097 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 525578.

The product of its (nonzero) digits is 2268, while the sum is 31.

The square root of 221091097 is about 14869.1323553192. The cubic root of 221091097 is about 604.6774201842.

The spelling of 221091097 in words is "two hundred twenty-one million, ninety-one thousand, ninety-seven".