221987281 has 8 divisors (see below), whose sum is σ = 225803520. Its totient is φ = 218185968.

The previous prime is 221987239. The next prime is 221987303. The reversal of 221987281 is 182789122.

221987281 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 a cyclic number.

It is not a de Polignac number, because 221987281 - 2⁷ = 221987153 is a prime.

It is a super-2 number, since 2×221987281² = 98556705851545922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221987201) 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, 28635 + ... + 35551.

It is an arithmetic number, because the mean of its divisors is an integer number (28225440).

Almost surely, 2^221987281 is an apocalyptic number.

It is an amenable number.

221987281 is a deficient number, since it is larger than the sum of its proper divisors (3816239).

221987281 is an equidigital number, since it uses as much as digits as its factorization.

221987281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7463.

The product of its digits is 32256, while the sum is 40.

The square root of 221987281 is about 14899.2375979444. The cubic root of 221987281 is about 605.4933307414.

The spelling of 221987281 in words is "two hundred twenty-one million, nine hundred eighty-seven thousand, two hundred eighty-one".