221506541 has 4 divisors (see below), whose sum is σ = 233164800. Its totient is φ = 209848284.

The previous prime is 221506511. The next prime is 221506543. The reversal of 221506541 is 145605122.

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 a de Polignac number, because none of the positive numbers 2^k-221506541 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 221506541.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221506543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5829101 + ... + 5829138.

It is an arithmetic number, because the mean of its divisors is an integer number (58291200).

Almost surely, 2^221506541 is an apocalyptic number.

It is an amenable number.

221506541 is a deficient number, since it is larger than the sum of its proper divisors (11658259).

221506541 is a wasteful number, since it uses less digits than its factorization.

221506541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11658258.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 221506541 is about 14883.0958137076. The cubic root of 221506541 is about 605.0559254360.

The spelling of 221506541 in words is "two hundred twenty-one million, five hundred six thousand, five hundred forty-one".