18908998081 has 2 divisors, whose sum is σ = 18908998082. Its totient is φ = 18908998080.

The previous prime is 18908998079. The next prime is 18908998139. The reversal of 18908998081 is 18089980981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18274713856 + 634284225 = 135184^2 + 25185^2 .

It is an emirp because it is prime and its reverse (18089980981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18908998081 - 2¹ = 18908998079 is a prime.

It is a super-2 number, since 2×18908998081² (a number of 21 digits) contains 22 as substring.

Together with 18908998079, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18908948081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9454499040 + 9454499041.

It is an arithmetic number, because the mean of its divisors is an integer number (9454499041).

Almost surely, 2^18908998081 is an apocalyptic number.

It is an amenable number.

18908998081 is a deficient number, since it is larger than the sum of its proper divisors (1).

18908998081 is an equidigital number, since it uses as much as digits as its factorization.

18908998081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2985984, while the sum is 61.

The spelling of 18908998081 in words is "eighteen billion, nine hundred eight million, nine hundred ninety-eight thousand, eighty-one".