221421242557 has 2 divisors, whose sum is σ = 221421242558. Its totient is φ = 221421242556.

The previous prime is 221421242543. The next prime is 221421242683. The reversal of 221421242557 is 755242124122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 204931857636 + 16489384921 = 452694^2 + 128411^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221421242557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221421242527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110710621278 + 110710621279.

It is an arithmetic number, because the mean of its divisors is an integer number (110710621279).

Almost surely, 2^221421242557 is an apocalyptic number.

It is an amenable number.

221421242557 is a deficient number, since it is larger than the sum of its proper divisors (1).

221421242557 is an equidigital number, since it uses as much as digits as its factorization.

221421242557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 89600, while the sum is 37.

Adding to 221421242557 its reverse (755242124122), we get a palindrome (976663366679).

The spelling of 221421242557 in words is "two hundred twenty-one billion, four hundred twenty-one million, two hundred forty-two thousand, five hundred fifty-seven".