1998188911 has 2 divisors, whose sum is σ = 1998188912. Its totient is φ = 1998188910.

The previous prime is 1998188909. The next prime is 1998188921. The reversal of 1998188911 is 1198818991.

It is a weak prime.

It is an emirp because it is prime and its reverse (1198818991) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1168818661 and 1668188611.

It is a cyclic number.

It is not a de Polignac number, because 1998188911 - 2¹ = 1998188909 is a prime.

It is a super-4 number, since 4×1998188911⁴ (a number of 38 digits) contains 4444 as substring.

Together with 1998188909, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1998188921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999094455 + 999094456.

It is an arithmetic number, because the mean of its divisors is an integer number (999094456).

Almost surely, 2^1998188911 is an apocalyptic number.

1998188911 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998188911 is an equidigital number, since it uses as much as digits as its factorization.

1998188911 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 55.

The square root of 1998188911 is about 44701.1063733326. The cubic root of 1998188911 is about 1259.5406301837.

The spelling of 1998188911 in words is "one billion, nine hundred ninety-eight million, one hundred eighty-eight thousand, nine hundred eleven".