99999999989881 has 2 divisors, whose sum is σ = 99999999989882. Its totient is φ = 99999999989880.

The previous prime is 99999999989783. The next prime is 99999999989887. The reversal of 99999999989881 is 18898999999999.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54509574963600 + 45490425026281 = 7383060^2 + 6744659^2 .

It is a cyclic number.

It is not a de Polignac number, because 99999999989881 - 2¹⁷ = 99999999858809 is a prime.

It is a super-2 number, since 2×99999999989881² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (99999999989887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49999999994940 + 49999999994941.

It is an arithmetic number, because the mean of its divisors is an integer number (49999999994941).

Almost surely, 2^{99999999989881} is an apocalyptic number.

It is an amenable number.

99999999989881 is a deficient number, since it is larger than the sum of its proper divisors (1).

99999999989881 is an equidigital number, since it uses as much as digits as its factorization.

99999999989881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1785233613312, while the sum is 115.

The spelling of 99999999989881 in words is "ninety-nine trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred eighty-nine thousand, eight hundred eighty-one".