221540505521 has 2 divisors, whose sum is σ = 221540505522. Its totient is φ = 221540505520.

The previous prime is 221540505491. The next prime is 221540505577. The reversal of 221540505521 is 125505045122.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187328824225 + 34211681296 = 432815^2 + 184964^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221540505521 is a prime.

It is not a weakly prime, because it can be changed into another prime (221540505421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110770252760 + 110770252761.

It is an arithmetic number, because the mean of its divisors is an integer number (110770252761).

Almost surely, 2^221540505521 is an apocalyptic number.

It is an amenable number.

221540505521 is a deficient number, since it is larger than the sum of its proper divisors (1).

221540505521 is an equidigital number, since it uses as much as digits as its factorization.

221540505521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20000, while the sum is 32.

The spelling of 221540505521 in words is "two hundred twenty-one billion, five hundred forty million, five hundred five thousand, five hundred twenty-one".