1989840 has 40 divisors (see below), whose sum is σ = 6169248. Its totient is φ = 530560.

The previous prime is 1989811. The next prime is 1989847. The reversal of 1989840 is 489891.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1989847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3906 + ... + 4385.

2^1989840 is an apocalyptic number.

1989840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1989840 is an abundant number, since it is smaller than the sum of its proper divisors (4179408).

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

1989840 is a wasteful number, since it uses less digits than its factorization.

1989840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8307 (or 8301 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 1989840 is about 1410.6168863302. The cubic root of 1989840 is about 125.7783960684.

The spelling of 1989840 in words is "one million, nine hundred eighty-nine thousand, eight hundred forty".