18921378 has 64 divisors (see below), whose sum is σ = 46126080. Its totient is φ = 5054400.

The previous prime is 18921373. The next prime is 18921379. The reversal of 18921378 is 87312981.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18921373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 104448 + ... + 104628.

It is an arithmetic number, because the mean of its divisors is an integer number (720720).

Almost surely, 2^18921378 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18921378, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23063040).

18921378 is an abundant number, since it is smaller than the sum of its proper divisors (27204702).

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

18921378 is a wasteful number, since it uses less digits than its factorization.

18921378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343.

The product of its digits is 24192, while the sum is 39.

The square root of 18921378 is about 4349.8710325710. The cubic root of 18921378 is about 266.4715944882.

The spelling of 18921378 in words is "eighteen million, nine hundred twenty-one thousand, three hundred seventy-eight".