998991121 has 2 divisors, whose sum is σ = 998991122. Its totient is φ = 998991120.

The previous prime is 998991107. The next prime is 998991167. The reversal of 998991121 is 121199899.

998991121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 825700225 + 173290896 = 28735^2 + 13164^2 .

It is a cyclic number.

It is not a de Polignac number, because 998991121 - 2⁹ = 998990609 is a prime.

It is not a weakly prime, because it can be changed into another prime (998991181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499495560 + 499495561.

It is an arithmetic number, because the mean of its divisors is an integer number (499495561).

Almost surely, 2^998991121 is an apocalyptic number.

It is an amenable number.

998991121 is a deficient number, since it is larger than the sum of its proper divisors (1).

998991121 is an equidigital number, since it uses as much as digits as its factorization.

998991121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 104976, while the sum is 49.

The square root of 998991121 is about 31606.8207986820. The cubic root of 998991121 is about 999.6635938436.

The spelling of 998991121 in words is "nine hundred ninety-eight million, nine hundred ninety-one thousand, one hundred twenty-one".