1998645 has 16 divisors (see below), whose sum is σ = 3488832. Its totient is φ = 968960.

The previous prime is 1998643. The next prime is 1998679. The reversal of 1998645 is 5468991.

It is not a de Polignac number, because 1998645 - 2¹ = 1998643 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1998597 and 1998606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5892 + ... + 6221.

It is an arithmetic number, because the mean of its divisors is an integer number (218052).

2^1998645 is an apocalyptic number.

1998645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1998645 is a deficient number, since it is larger than the sum of its proper divisors (1490187).

1998645 is a wasteful number, since it uses less digits than its factorization.

1998645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12132.

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

The square root of 1998645 is about 1413.7344163597. The cubic root of 1998645 is about 125.9636453443.

The spelling of 1998645 in words is "one million, nine hundred ninety-eight thousand, six hundred forty-five".