221639591 has 12 divisors (see below), whose sum is σ = 236402280. Its totient is φ = 207753600.

The previous prime is 221639581. The next prime is 221639597. The reversal of 221639591 is 195936122.

It is not a de Polignac number, because 221639591 - 2¹⁰ = 221638567 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221639597) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 76316 + ... + 79166.

It is an arithmetic number, because the mean of its divisors is an integer number (19700190).

Almost surely, 2^221639591 is an apocalyptic number.

221639591 is a deficient number, since it is larger than the sum of its proper divisors (14762689).

221639591 is a wasteful number, since it uses less digits than its factorization.

221639591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3154 (or 3137 counting only the distinct ones).

The product of its digits is 29160, while the sum is 38.

The square root of 221639591 is about 14887.5649788674. The cubic root of 221639591 is about 605.1770453777.

The spelling of 221639591 in words is "two hundred twenty-one million, six hundred thirty-nine thousand, five hundred ninety-one".