18371615557 has 2 divisors, whose sum is σ = 18371615558. Its totient is φ = 18371615556.

The previous prime is 18371615551. The next prime is 18371615567. The reversal of 18371615557 is 75551617381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12990072676 + 5381542881 = 113974^2 + 73359^2 .

It is an emirp because it is prime and its reverse (75551617381) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18371615557 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18371615557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18371615551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9185807778 + 9185807779.

It is an arithmetic number, because the mean of its divisors is an integer number (9185807779).

Almost surely, 2^18371615557 is an apocalyptic number.

It is an amenable number.

18371615557 is a deficient number, since it is larger than the sum of its proper divisors (1).

18371615557 is an equidigital number, since it uses as much as digits as its factorization.

18371615557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 882000, while the sum is 49.

The spelling of 18371615557 in words is "eighteen billion, three hundred seventy-one million, six hundred fifteen thousand, five hundred fifty-seven".