1999640 has 16 divisors (see below), whose sum is σ = 4499280. Its totient is φ = 799840.

The previous prime is 1999633. The next prime is 1999651. The reversal of 1999640 is 469991.

It is a zygodrome in base 7.

It is a junction number, because it is equal to n+sod(n) for n = 1999594 and 1999603.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24956 + ... + 25035.

It is an arithmetic number, because the mean of its divisors is an integer number (281205).

2^1999640 is an apocalyptic number.

1999640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1999640 is an abundant number, since it is smaller than the sum of its proper divisors (2499640).

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

1999640 is a wasteful number, since it uses less digits than its factorization.

1999640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50002 (or 49998 counting only the distinct ones).

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 1999640 is about 1414.0862774244. The cubic root of 1999640 is about 125.9845450096.

The spelling of 1999640 in words is "one million, nine hundred ninety-nine thousand, six hundred forty".