1998945 has 64 divisors (see below), whose sum is σ = 4112640. Its totient is φ = 912384.

The previous prime is 1998943. The next prime is 1998947. The reversal of 1998945 is 5498991.

It is an interprime number because it is at equal distance from previous prime (1998943) and next prime (1998947).

It is not a de Polignac number, because 1998945 - 2¹ = 1998943 is a prime.

It is a super-2 number, since 2×1998945² = 7991562226050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an Ulam number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1998945.

It is not an unprimeable number, because it can be changed into a prime (1998943) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 29802 + ... + 29868.

It is an arithmetic number, because the mean of its divisors is an integer number (64260).

2^1998945 is an apocalyptic number.

1998945 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1998945 is an abundant number, since it is smaller than the sum of its proper divisors (2113695).

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

1998945 is a wasteful number, since it uses less digits than its factorization.

1998945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111 (or 105 counting only the distinct ones).

The product of its digits is 116640, while the sum is 45.

The square root of 1998945 is about 1413.8405143438. The cubic root of 1998945 is about 125.9699474812.

The spelling of 1998945 in words is "one million, nine hundred ninety-eight thousand, nine hundred forty-five".