11515136615221 has 2 divisors, whose sum is σ = 11515136615222. Its totient is φ = 11515136615220.

The previous prime is 11515136615219. The next prime is 11515136615287. The reversal of 11515136615221 is 12251663151511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6220604644996 + 5294531970225 = 2494114^2 + 2300985^2 .

It is a cyclic number.

It is not a de Polignac number, because 11515136615221 - 2¹ = 11515136615219 is a prime.

Together with 11515136615219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11515136610221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5757568307610 + 5757568307611.

It is an arithmetic number, because the mean of its divisors is an integer number (5757568307611).

Almost surely, 2^{11515136615221} is an apocalyptic number.

It is an amenable number.

11515136615221 is a deficient number, since it is larger than the sum of its proper divisors (1).

11515136615221 is an equidigital number, since it uses as much as digits as its factorization.

11515136615221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54000, while the sum is 40.

Adding to 11515136615221 its reverse (12251663151511), we get a palindrome (23766799766732).

The spelling of 11515136615221 in words is "eleven trillion, five hundred fifteen billion, one hundred thirty-six million, six hundred fifteen thousand, two hundred twenty-one".