18000038999981 has 2 divisors, whose sum is σ = 18000038999982. Its totient is φ = 18000038999980.

The previous prime is 18000038999951. The next prime is 18000039000037. The reversal of 18000038999981 is 18999983000081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16275455461225 + 1724583538756 = 4034285^2 + 1313234^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18000038999981 is a prime.

It is a super-2 number, since 2×18000038999981² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18000038999951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9000019499990 + 9000019499991.

It is an arithmetic number, because the mean of its divisors is an integer number (9000019499991).

Almost surely, 2^{18000038999981} is an apocalyptic number.

It is an amenable number.

18000038999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

18000038999981 is an equidigital number, since it uses as much as digits as its factorization.

18000038999981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10077696, while the sum is 65.

The spelling of 18000038999981 in words is "eighteen trillion, thirty-eight million, nine hundred ninety-nine thousand, nine hundred eighty-one".