1989945 has 12 divisors (see below), whose sum is σ = 3449316. Its totient is φ = 1061280.

The previous prime is 1989919. The next prime is 1989947. The reversal of 1989945 is 5499891.

It can be written as a sum of positive squares in 2 ways, for example, as 1505529 + 484416 = 1227^2 + 696^2 .

It is not a de Polignac number, because 1989945 - 2¹² = 1985849 is a prime.

It is a super-2 number, since 2×1989945² = 7919762206050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 44221 = 1989945 / (1 + 9 + 8 + 9 + 9 + 4 + 5).

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 1989945.

It is not an unprimeable number, because it can be changed into a prime (1989947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22066 + ... + 22155.

It is an arithmetic number, because the mean of its divisors is an integer number (287443).

2^1989945 is an apocalyptic number.

1989945 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1989945 is a deficient number, since it is larger than the sum of its proper divisors (1459371).

1989945 is a wasteful number, since it uses less digits than its factorization.

1989945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44232 (or 44229 counting only the distinct ones).

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

The square root of 1989945 is about 1410.6541035988. The cubic root of 1989945 is about 125.7806083902.

The spelling of 1989945 in words is "one million, nine hundred eighty-nine thousand, nine hundred forty-five".