18013751981 has 2 divisors, whose sum is σ = 18013751982. Its totient is φ = 18013751980.

The previous prime is 18013751881. The next prime is 18013752013. The reversal of 18013751981 is 18915731081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17669055625 + 344696356 = 132925^2 + 18566^2 .

It is a cyclic number.

It is not a de Polignac number, because 18013751981 - 2¹⁰ = 18013750957 is a prime.

It is a super-2 number, since 2×18013751981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18013751081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9006875990 + 9006875991.

It is an arithmetic number, because the mean of its divisors is an integer number (9006875991).

Almost surely, 2^18013751981 is an apocalyptic number.

It is an amenable number.

18013751981 is a deficient number, since it is larger than the sum of its proper divisors (1).

18013751981 is an equidigital number, since it uses as much as digits as its factorization.

18013751981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60480, while the sum is 44.

The spelling of 18013751981 in words is "eighteen billion, thirteen million, seven hundred fifty-one thousand, nine hundred eighty-one".