1998423081 has 6 divisors (see below), whose sum is σ = 2886611130. Its totient is φ = 1332282048.

The previous prime is 1998423041. The next prime is 1998423139. The reversal of 1998423081 is 1803248991.

It can be written as a sum of positive squares in only one way, i.e., 1966035600 + 32387481 = 44340^2 + 5691^2 .

It is not a de Polignac number, because 1998423081 - 2²⁵ = 1964868649 is a prime.

It is a super-2 number, since 2×1998423081² = 7987389621347065122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1998423001) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 111023496 + ... + 111023513.

It is an arithmetic number, because the mean of its divisors is an integer number (481101855).

Almost surely, 2^1998423081 is an apocalyptic number.

It is an amenable number.

1998423081 is a deficient number, since it is larger than the sum of its proper divisors (888188049).

1998423081 is a wasteful number, since it uses less digits than its factorization.

1998423081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222047015 (or 222047012 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 1998423081 is about 44703.7255829981. The cubic root of 1998423081 is about 1259.5898305883.

The spelling of 1998423081 in words is "one billion, nine hundred ninety-eight million, four hundred twenty-three thousand, eighty-one".