1998353381 has 4 divisors (see below), whose sum is σ = 1998457164. Its totient is φ = 1998249600.

The previous prime is 1998353363. The next prime is 1998353389. The reversal of 1998353381 is 1833538991.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1833538991 = 6581 ⋅278611.

It can be written as a sum of positive squares in 2 ways, for example, as 1555040356 + 443313025 = 39434^2 + 21055^2 .

It is a cyclic number.

It is not a de Polignac number, because 1998353381 - 2¹⁰ = 1998352357 is a prime.

It is a super-2 number, since 2×1998353381² = 7986832470708262322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998353389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13580 + ... + 64661.

It is an arithmetic number, because the mean of its divisors is an integer number (499614291).

Almost surely, 2^1998353381 is an apocalyptic number.

It is an amenable number.

1998353381 is a deficient number, since it is larger than the sum of its proper divisors (103783).

1998353381 is an equidigital number, since it uses as much as digits as its factorization.

1998353381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103782.

The product of its digits is 699840, while the sum is 50.

The square root of 1998353381 is about 44702.9459991173. The cubic root of 1998353381 is about 1259.5751866368.

The spelling of 1998353381 in words is "one billion, nine hundred ninety-eight million, three hundred fifty-three thousand, three hundred eighty-one".