221242251 has 8 divisors (see below), whose sum is σ = 310515520. Its totient is φ = 139731912.

The previous prime is 221242243. The next prime is 221242283. The reversal of 221242251 is 152242122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 221242251 - 2³ = 221242243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221242201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1940665 + ... + 1940778.

It is an arithmetic number, because the mean of its divisors is an integer number (38814440).

Almost surely, 2^221242251 is an apocalyptic number.

221242251 is a deficient number, since it is larger than the sum of its proper divisors (89273269).

221242251 is a wasteful number, since it uses less digits than its factorization.

221242251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3881465.

The product of its digits is 640, while the sum is 21.

The square root of 221242251 is about 14874.2142985773. The cubic root of 221242251 is about 604.8151893222.

Adding to 221242251 its reverse (152242122), we get a palindrome (373484373).

The spelling of 221242251 in words is "two hundred twenty-one million, two hundred forty-two thousand, two hundred fifty-one".