221989491 has 24 divisors (see below), whose sum is σ = 346993920. Its totient is φ = 141554952.

The previous prime is 221989489. The next prime is 221989501. The reversal of 221989491 is 194989122.

221989491 is nontrivially palindromic in base 6.

It is not a de Polignac number, because 221989491 - 2¹ = 221989489 is a prime.

It is a super-2 number, since 2×221989491² = 98558668228878162, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (221989421) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14271 + ... + 25448.

It is an arithmetic number, because the mean of its divisors is an integer number (14458080).

Almost surely, 2^221989491 is an apocalyptic number.

221989491 is a deficient number, since it is larger than the sum of its proper divisors (125004429).

221989491 is an equidigital number, since it uses as much as digits as its factorization.

221989491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39757 (or 39745 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 221989491 is about 14899.3117626285. The cubic root of 221989491 is about 605.4953400695.

The spelling of 221989491 in words is "two hundred twenty-one million, nine hundred eighty-nine thousand, four hundred ninety-one".