221631541 has 4 divisors (see below), whose sum is σ = 224753184. Its totient is φ = 218509900.

The previous prime is 221631539. The next prime is 221631551. The reversal of 221631541 is 145136122.

It is a happy number.

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 221631541 - 2¹ = 221631539 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 (221631551) 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, 1560715 + ... + 1560856.

It is an arithmetic number, because the mean of its divisors is an integer number (56188296).

Almost surely, 2^221631541 is an apocalyptic number.

It is an amenable number.

221631541 is a deficient number, since it is larger than the sum of its proper divisors (3121643).

221631541 is an equidigital number, since it uses as much as digits as its factorization.

221631541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3121642.

The product of its digits is 1440, while the sum is 25.

The square root of 221631541 is about 14887.2946165514. The cubic root of 221631541 is about 605.1697185667.

Adding to 221631541 its reverse (145136122), we get a palindrome (366767663).

The spelling of 221631541 in words is "two hundred twenty-one million, six hundred thirty-one thousand, five hundred forty-one".