1999820 has 12 divisors (see below), whose sum is σ = 4199664. Its totient is φ = 799920.

The previous prime is 1999819. The next prime is 1999853. The reversal of 1999820 is 289991.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 49976 + ... + 50015.

It is an arithmetic number, because the mean of its divisors is an integer number (349972).

2^1999820 is an apocalyptic number.

1999820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1999820 is an abundant number, since it is smaller than the sum of its proper divisors (2199844).

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

1999820 is a wasteful number, since it uses less digits than its factorization.

1999820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100000 (or 99998 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 1999820 is about 1414.1499213308. The cubic root of 1999820 is about 125.9883251129.

The spelling of 1999820 in words is "one million, nine hundred ninety-nine thousand, eight hundred twenty".