18315561497 has 2 divisors, whose sum is σ = 18315561498. Its totient is φ = 18315561496.

The previous prime is 18315561491. The next prime is 18315561547. The reversal of 18315561497 is 79416551381.

It is an a-pointer prime, because the next prime (18315561547) can be obtained adding 18315561497 to its sum of digits (50).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15368808841 + 2946752656 = 123971^2 + 54284^2 .

It is a cyclic number.

It is not a de Polignac number, because 18315561497 - 2¹² = 18315557401 is a prime.

It is not a weakly prime, because it can be changed into another prime (18315561491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9157780748 + 9157780749.

It is an arithmetic number, because the mean of its divisors is an integer number (9157780749).

Almost surely, 2^18315561497 is an apocalyptic number.

It is an amenable number.

18315561497 is a deficient number, since it is larger than the sum of its proper divisors (1).

18315561497 is an equidigital number, since it uses as much as digits as its factorization.

18315561497 is an evil number, because the sum of its binary digits is even.

The product of its digits is 907200, while the sum is 50.

The spelling of 18315561497 in words is "eighteen billion, three hundred fifteen million, five hundred sixty-one thousand, four hundred ninety-seven".