221631643 has 2 divisors, whose sum is σ = 221631644. Its totient is φ = 221631642.

The previous prime is 221631629. The next prime is 221631653. The reversal of 221631643 is 346136122.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 221631643 - 2⁹ = 221631131 is a prime.

It is not a weakly prime, because it can be changed into another prime (221631653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110815821 + 110815822.

It is an arithmetic number, because the mean of its divisors is an integer number (110815822).

Almost surely, 2^221631643 is an apocalyptic number.

221631643 is a deficient number, since it is larger than the sum of its proper divisors (1).

221631643 is an equidigital number, since it uses as much as digits as its factorization.

221631643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 28.

The square root of 221631643 is about 14887.2980422910. The cubic root of 221631643 is about 605.1698114044.

Adding to 221631643 its reverse (346136122), we get a palindrome (567767765).

The spelling of 221631643 in words is "two hundred twenty-one million, six hundred thirty-one thousand, six hundred forty-three".