1999980 has 72 divisors (see below), whose sum is σ = 6237504. Its totient is φ = 518400.

The previous prime is 1999979. The next prime is 1999993. The reversal of 1999980 is 899991.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7245 + ... + 7515.

It is an arithmetic number, because the mean of its divisors is an integer number (86632).

2^1999980 is an apocalyptic number.

1999980 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 1999980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3118752).

1999980 is an abundant number, since it is smaller than the sum of its proper divisors (4237524).

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

1999980 is a wasteful number, since it uses less digits than its factorization.

1999980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327 (or 322 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 45.

The square root of 1999980 is about 1414.2064912876. The cubic root of 1999980 is about 125.9916850144.

1999980 divided by its sum of digits (45) gives a palindrome (44444).

It can be divided in two parts, 19 and 99980, that added together give a palindrome (99999).

The spelling of 1999980 in words is "one million, nine hundred ninety-nine thousand, nine hundred eighty".