13891817521 has 2 divisors, whose sum is σ = 13891817522. Its totient is φ = 13891817520.

The previous prime is 13891817509. The next prime is 13891817531. The reversal of 13891817521 is 12571819831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12563943921 + 1327873600 = 112089^2 + 36440^2 .

It is an emirp because it is prime and its reverse (12571819831) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13891817521 is a prime.

It is not a weakly prime, because it can be changed into another prime (13891817531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6945908760 + 6945908761.

It is an arithmetic number, because the mean of its divisors is an integer number (6945908761).

Almost surely, 2^13891817521 is an apocalyptic number.

It is an amenable number.

13891817521 is a deficient number, since it is larger than the sum of its proper divisors (1).

13891817521 is an equidigital number, since it uses as much as digits as its factorization.

13891817521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 46.

The spelling of 13891817521 in words is "thirteen billion, eight hundred ninety-one million, eight hundred seventeen thousand, five hundred twenty-one".