1999920 has 80 divisors (see below), whose sum is σ = 6687072. Its totient is φ = 491520.

The previous prime is 1999891. The next prime is 1999957. The reversal of 1999920 is 299991.

1999920 = T₂₁ + T₂₂ + ... + T₂₂₈.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an Ulam number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2800 + ... + 3440.

2^1999920 is an apocalyptic number.

1999920 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 1999920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3343536).

1999920 is an abundant number, since it is smaller than the sum of its proper divisors (4687152).

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

1999920 is a wasteful number, since it uses less digits than its factorization.

1999920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 670 (or 664 counting only the distinct ones).

The product of its (nonzero) digits is 13122, while the sum is 39.

The square root of 1999920 is about 1414.1852778190. The cubic root of 1999920 is about 125.9904250724.

The spelling of 1999920 in words is "one million, nine hundred ninety-nine thousand, nine hundred twenty".