221220291 has 4 divisors (see below), whose sum is σ = 294960392. Its totient is φ = 147480192.

The previous prime is 221220289. The next prime is 221220301. The reversal of 221220291 is 192022122.

It is a happy number.

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

It is not a de Polignac number, because 221220291 - 2¹ = 221220289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221220491) 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, 36870046 + ... + 36870051.

It is an arithmetic number, because the mean of its divisors is an integer number (73740098).

Almost surely, 2^221220291 is an apocalyptic number.

221220291 is a deficient number, since it is larger than the sum of its proper divisors (73740101).

221220291 is an equidigital number, since it uses as much as digits as its factorization.

221220291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73740100.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 221220291 is about 14873.4760900067. The cubic root of 221220291 is about 604.7951778025.

The spelling of 221220291 in words is "two hundred twenty-one million, two hundred twenty thousand, two hundred ninety-one".