18389778 has 32 divisors (see below), whose sum is σ = 40642560. Its totient is φ = 5500560.

The previous prime is 18389759. The next prime is 18389779. The reversal of 18389778 is 87798381.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18389778.

It is not an unprimeable number, because it can be changed into a prime (18389779) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3451 + ... + 6977.

It is an arithmetic number, because the mean of its divisors is an integer number (1270080).

Almost surely, 2^18389778 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18389778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20321280).

18389778 is an abundant number, since it is smaller than the sum of its proper divisors (22252782).

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

18389778 is a wasteful number, since it uses less digits than its factorization.

18389778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3622.

The product of its digits is 677376, while the sum is 51.

The square root of 18389778 is about 4288.3304443571. The cubic root of 18389778 is about 263.9523272504.

The spelling of 18389778 in words is "eighteen million, three hundred eighty-nine thousand, seven hundred seventy-eight".