221543641 has 4 divisors (see below), whose sum is σ = 241683984. Its totient is φ = 201403300.

The previous prime is 221543603. The next prime is 221543653. The reversal of 221543641 is 146345122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221543641 - 2⁷ = 221543513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221543671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10070155 + ... + 10070176.

It is an arithmetic number, because the mean of its divisors is an integer number (60420996).

Almost surely, 2^221543641 is an apocalyptic number.

It is an amenable number.

221543641 is a deficient number, since it is larger than the sum of its proper divisors (20140343).

221543641 is a wasteful number, since it uses less digits than its factorization.

221543641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20140342.

The product of its digits is 5760, while the sum is 28.

The square root of 221543641 is about 14884.3421419961. The cubic root of 221543641 is about 605.0897037037.

Adding to 221543641 its reverse (146345122), we get a palindrome (367888763).

The spelling of 221543641 in words is "two hundred twenty-one million, five hundred forty-three thousand, six hundred forty-one".