1999840 has 48 divisors (see below), whose sum is σ = 4898880. Its totient is φ = 770560.

The previous prime is 1999819. The next prime is 1999853. The reversal of 1999840 is 489991.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 1999793 and 1999802.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4425 + ... + 4855.

It is an arithmetic number, because the mean of its divisors is an integer number (102060).

2^1999840 is an apocalyptic number.

1999840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1999840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2449440).

1999840 is an abundant number, since it is smaller than the sum of its proper divisors (2899040).

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

1999840 is a wasteful number, since it uses less digits than its factorization.

1999840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 475 (or 467 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 1999840 is about 1414.1569926992. The cubic root of 1999840 is about 125.9887451104.

The spelling of 1999840 in words is "one million, nine hundred ninety-nine thousand, eight hundred forty".