1998564 has 24 divisors (see below), whose sum is σ = 4824960. Its totient is φ = 643104.

The previous prime is 1998559. The next prime is 1998569. The reversal of 1998564 is 4658991.

It is an interprime number because it is at equal distance from previous prime (1998559) and next prime (1998569).

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998569) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2524 + ... + 3219.

It is an arithmetic number, because the mean of its divisors is an integer number (201040).

2^1998564 is an apocalyptic number.

It is an amenable number.

1998564 is an abundant number, since it is smaller than the sum of its proper divisors (2826396).

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

1998564 is a wasteful number, since it uses less digits than its factorization.

1998564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5779 (or 5777 counting only the distinct ones).

The product of its digits is 77760, while the sum is 42.

The square root of 1998564 is about 1413.7057685388. The cubic root of 1998564 is about 125.9619436593.

The spelling of 1998564 in words is "one million, nine hundred ninety-eight thousand, five hundred sixty-four".