221366591 has 2 divisors, whose sum is σ = 221366592. Its totient is φ = 221366590.

The previous prime is 221366539. The next prime is 221366603. The reversal of 221366591 is 195663122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221366591 - 2¹⁰ = 221365567 is a prime.

It is a super-2 number, since 2×221366591² = 98006335221922562, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221366501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110683295 + 110683296.

It is an arithmetic number, because the mean of its divisors is an integer number (110683296).

Almost surely, 2^221366591 is an apocalyptic number.

221366591 is a deficient number, since it is larger than the sum of its proper divisors (1).

221366591 is an equidigital number, since it uses as much as digits as its factorization.

221366591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440, while the sum is 35.

The square root of 221366591 is about 14878.3934280553. The cubic root of 221366591 is about 604.9284718387.

The spelling of 221366591 in words is "two hundred twenty-one million, three hundred sixty-six thousand, five hundred ninety-one".