99121989121 has 2 divisors, whose sum is σ = 99121989122. Its totient is φ = 99121989120.

The previous prime is 99121989103. The next prime is 99121989179. The reversal of 99121989121 is 12198912199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 98950510096 + 171479025 = 314564^2 + 13095^2 .

It is an emirp because it is prime and its reverse (12198912199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 99121989121 - 2⁷ = 99121988993 is a prime.

It is not a weakly prime, because it can be changed into another prime (99121989191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49560994560 + 49560994561.

It is an arithmetic number, because the mean of its divisors is an integer number (49560994561).

Almost surely, 2^99121989121 is an apocalyptic number.

It is an amenable number.

99121989121 is a deficient number, since it is larger than the sum of its proper divisors (1).

99121989121 is an equidigital number, since it uses as much as digits as its factorization.

99121989121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209952, while the sum is 52.

The spelling of 99121989121 in words is "ninety-nine billion, one hundred twenty-one million, nine hundred eighty-nine thousand, one hundred twenty-one".