18688377781 has 2 divisors, whose sum is σ = 18688377782. Its totient is φ = 18688377780.

The previous prime is 18688377769. The next prime is 18688377793. The reversal of 18688377781 is 18777388681.

It is a balanced prime because it is at equal distance from previous prime (18688377769) and next prime (18688377793).

It can be written as a sum of positive squares in only one way, i.e., 13555944900 + 5132432881 = 116430^2 + 71641^2 .

It is a cyclic number.

It is not a de Polignac number, because 18688377781 - 2²¹ = 18686280629 is a prime.

It is a super-2 number, since 2×18688377781² (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 (18688377761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9344188890 + 9344188891.

It is an arithmetic number, because the mean of its divisors is an integer number (9344188891).

Almost surely, 2^18688377781 is an apocalyptic number.

It is an amenable number.

18688377781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18688377781 is an equidigital number, since it uses as much as digits as its factorization.

18688377781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25288704, while the sum is 64.

The spelling of 18688377781 in words is "eighteen billion, six hundred eighty-eight million, three hundred seventy-seven thousand, seven hundred eighty-one".