221315257 has 2 divisors, whose sum is σ = 221315258. Its totient is φ = 221315256.

The previous prime is 221315251. The next prime is 221315273. The reversal of 221315257 is 752513122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 221295376 + 19881 = 14876^2 + 141^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221315257 is a prime.

It is not a weakly prime, because it can be changed into another prime (221315251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110657628 + 110657629.

It is an arithmetic number, because the mean of its divisors is an integer number (110657629).

Almost surely, 2^221315257 is an apocalyptic number.

It is an amenable number.

221315257 is a deficient number, since it is larger than the sum of its proper divisors (1).

221315257 is an equidigital number, since it uses as much as digits as its factorization.

221315257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4200, while the sum is 28.

The square root of 221315257 is about 14876.6682089774. The cubic root of 221315257 is about 604.8817080841.

Adding to 221315257 its reverse (752513122), we get a palindrome (973828379).

The spelling of 221315257 in words is "two hundred twenty-one million, three hundred fifteen thousand, two hundred fifty-seven".