221993591 has 2 divisors, whose sum is σ = 221993592. Its totient is φ = 221993590.

The previous prime is 221993537. The next prime is 221993621. The reversal of 221993591 is 195399122.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221993591 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221963591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110996795 + 110996796.

It is an arithmetic number, because the mean of its divisors is an integer number (110996796).

Almost surely, 2^221993591 is an apocalyptic number.

221993591 is a deficient number, since it is larger than the sum of its proper divisors (1).

221993591 is an equidigital number, since it uses as much as digits as its factorization.

221993591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43740, while the sum is 41.

The square root of 221993591 is about 14899.4493522412. The cubic root of 221993591 is about 605.4990677469.

The spelling of 221993591 in words is "two hundred twenty-one million, nine hundred ninety-three thousand, five hundred ninety-one".