18919980 has 144 divisors (see below), whose sum is σ = 63292320. Its totient is φ = 4727808.

The previous prime is 18919973. The next prime is 18919981. The reversal of 18919980 is 8991981.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

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

It is not an unprimeable number, because it can be changed into a prime (18919981) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 82506 + ... + 82734.

It is an arithmetic number, because the mean of its divisors is an integer number (439530).

Almost surely, 2^18919980 is an apocalyptic number.

18919980 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 18919980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31646160).

18919980 is an abundant number, since it is smaller than the sum of its proper divisors (44372340).

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

18919980 is a wasteful number, since it uses less digits than its factorization.

18919980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270 (or 256 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 45.

The square root of 18919980 is about 4349.7103351833. The cubic root of 18919980 is about 266.4650316036.

The spelling of 18919980 in words is "eighteen million, nine hundred nineteen thousand, nine hundred eighty".