221289891 has 8 divisors (see below), whose sum is σ = 296151120. Its totient is φ = 146977632.

The previous prime is 221289853. The next prime is 221289899. The reversal of 221289891 is 198982122.

221289891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 221289891 - 2⁷ = 221289763 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221289899) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 136300 + ... + 137913.

It is an arithmetic number, because the mean of its divisors is an integer number (37018890).

Almost surely, 2^221289891 is an apocalyptic number.

221289891 is a deficient number, since it is larger than the sum of its proper divisors (74861229).

221289891 is a wasteful number, since it uses less digits than its factorization.

221289891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274485.

The product of its digits is 41472, while the sum is 42.

The square root of 221289891 is about 14875.8156415035. The cubic root of 221289891 is about 604.8585977393.

The spelling of 221289891 in words is "two hundred twenty-one million, two hundred eighty-nine thousand, eight hundred ninety-one".