186618442751981 has 2 divisors, whose sum is σ = 186618442751982. Its totient is φ = 186618442751980.

The previous prime is 186618442751929. The next prime is 186618442752013. The reversal of 186618442751981 is 189157244816681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 137173497227881 + 49444945524100 = 11712109^2 + 7031710^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-186618442751981 is a prime.

It is a super-2 number, since 2×186618442751981² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (186618442751911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 93309221375990 + 93309221375991.

It is an arithmetic number, because the mean of its divisors is an integer number (93309221375991).

Almost surely, 2^{186618442751981} is an apocalyptic number.

It is an amenable number.

186618442751981 is a deficient number, since it is larger than the sum of its proper divisors (1).

186618442751981 is an equidigital number, since it uses as much as digits as its factorization.

186618442751981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 185794560, while the sum is 71.

The spelling of 186618442751981 in words is "one hundred eighty-six trillion, six hundred eighteen billion, four hundred forty-two million, seven hundred fifty-one thousand, nine hundred eighty-one".