15645243221 has 2 divisors, whose sum is σ = 15645243222. Its totient is φ = 15645243220.

The previous prime is 15645243203. The next prime is 15645243223. The reversal of 15645243221 is 12234254651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10741042321 + 4904200900 = 103639^2 + 70030^2 .

It is a cyclic number.

It is not a de Polignac number, because 15645243221 - 2²⁶ = 15578134357 is a prime.

Together with 15645243223, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15645243223) 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 as a sum of consecutive naturals, namely, 7822621610 + 7822621611.

It is an arithmetic number, because the mean of its divisors is an integer number (7822621611).

Almost surely, 2^15645243221 is an apocalyptic number.

It is an amenable number.

15645243221 is a deficient number, since it is larger than the sum of its proper divisors (1).

15645243221 is an equidigital number, since it uses as much as digits as its factorization.

15645243221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 57600, while the sum is 35.

Adding to 15645243221 its reverse (12234254651), we get a palindrome (27879497872).

The spelling of 15645243221 in words is "fifteen billion, six hundred forty-five million, two hundred forty-three thousand, two hundred twenty-one".