19980000 has 240 divisors, whose sum is σ = 74788560. Its totient is φ = 5184000.

The previous prime is 19979987. The next prime is 19980019. The reversal of 19980000 is 8991.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 539982 + ... + 540018.

It is an arithmetic number, because the mean of its divisors is an integer number (311619).

Almost surely, 2^19980000 is an apocalyptic number.

19980000 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 19980000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37394280).

19980000 is an abundant number, since it is smaller than the sum of its proper divisors (54808560).

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

19980000 is an equidigital number, since it uses as much as digits as its factorization.

19980000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 19980000 is about 4469.8993277254. The cubic root of 19980000 is about 271.3512508953.

Adding to 19980000 its reverse (8991), we get a palindrome (19988991).

The spelling of 19980000 in words is "nineteen million, nine hundred eighty thousand".