18538361381 has 2 divisors, whose sum is σ = 18538361382. Its totient is φ = 18538361380.

The previous prime is 18538361377. The next prime is 18538361407. The reversal of 18538361381 is 18316383581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17143712356 + 1394649025 = 130934^2 + 37345^2 .

It is a cyclic number.

It is not a de Polignac number, because 18538361381 - 2² = 18538361377 is a prime.

It is a super-2 number, since 2×18538361381² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18538361311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9269180690 + 9269180691.

It is an arithmetic number, because the mean of its divisors is an integer number (9269180691).

Almost surely, 2^18538361381 is an apocalyptic number.

It is an amenable number.

18538361381 is a deficient number, since it is larger than the sum of its proper divisors (1).

18538361381 is an equidigital number, since it uses as much as digits as its factorization.

18538361381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 414720, while the sum is 47.

The spelling of 18538361381 in words is "eighteen billion, five hundred thirty-eight million, three hundred sixty-one thousand, three hundred eighty-one".