18487944657109 has 2 divisors, whose sum is σ = 18487944657110. Its totient is φ = 18487944657108.

The previous prime is 18487944657097. The next prime is 18487944657131. The reversal of 18487944657109 is 90175644978481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12732158286225 + 5755786370884 = 3568215^2 + 2399122^2 .

It is a cyclic number.

It is not a de Polignac number, because 18487944657109 - 2¹³ = 18487944648917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18487944657179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9243972328554 + 9243972328555.

It is an arithmetic number, because the mean of its divisors is an integer number (9243972328555).

Almost surely, 2^{18487944657109} is an apocalyptic number.

It is an amenable number.

18487944657109 is a deficient number, since it is larger than the sum of its proper divisors (1).

18487944657109 is an equidigital number, since it uses as much as digits as its factorization.

18487944657109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 487710720, while the sum is 73.

The spelling of 18487944657109 in words is "eighteen trillion, four hundred eighty-seven billion, nine hundred forty-four million, six hundred fifty-seven thousand, one hundred nine".