18800781121 has 2 divisors, whose sum is σ = 18800781122. Its totient is φ = 18800781120.

The previous prime is 18800781073. The next prime is 18800781137. The reversal of 18800781121 is 12118700881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17838540721 + 962240400 = 133561^2 + 31020^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18800781121 is a prime.

It is not a weakly prime, because it can be changed into another prime (18800781161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9400390560 + 9400390561.

It is an arithmetic number, because the mean of its divisors is an integer number (9400390561).

Almost surely, 2^18800781121 is an apocalyptic number.

It is an amenable number.

18800781121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18800781121 is an equidigital number, since it uses as much as digits as its factorization.

18800781121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7168, while the sum is 37.

The spelling of 18800781121 in words is "eighteen billion, eight hundred million, seven hundred eighty-one thousand, one hundred twenty-one".