18921000 has 256 divisors, whose sum is σ = 72783360. Its totient is φ = 3993600.

The previous prime is 18920987. The next prime is 18921011. The reversal of 18921000 is 12981.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 356974 + ... + 357026.

It is an arithmetic number, because the mean of its divisors is an integer number (284310).

Almost surely, 2^18921000 is an apocalyptic number.

18921000 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 18921000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36391680).

18921000 is an abundant number, since it is smaller than the sum of its proper divisors (53862360).

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

18921000 is a wasteful number, since it uses less digits than its factorization.

18921000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101 (or 87 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 18921000 is about 4349.8275827899. The cubic root of 18921000 is about 266.4698200063.

Adding to 18921000 its reverse (12981), we get a palindrome (18933981).

The spelling of 18921000 in words is "eighteen million, nine hundred twenty-one thousand".