1998558 has 12 divisors (see below), whose sum is σ = 4330248. Its totient is φ = 666180.

The previous prime is 1998541. The next prime is 1998559. The reversal of 1998558 is 8558991.

1998558 is a `hidden beast` number, since 1 + 9 + 98 + 558 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998559) 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, 55498 + ... + 55533.

It is an arithmetic number, because the mean of its divisors is an integer number (360854).

2^1998558 is an apocalyptic number.

1998558 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1998558 is an abundant number, since it is smaller than the sum of its proper divisors (2331690).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1998558 is a wasteful number, since it uses less digits than its factorization.

1998558 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111039 (or 111036 counting only the distinct ones).

The product of its digits is 129600, while the sum is 45.

The square root of 1998558 is about 1413.7036464549. The cubic root of 1998558 is about 125.9618176067.

It can be divided in two parts, 1998 and 558, that added together give a triangular number (2556 = T₇₁).

The spelling of 1998558 in words is "one million, nine hundred ninety-eight thousand, five hundred fifty-eight".