18397638 has 96 divisors (see below), whose sum is σ = 50479200. Its totient is φ = 4935168.

The previous prime is 18397637. The next prime is 18397649. The reversal of 18397638 is 83679381.

It is a happy number.

18397638 is a `hidden beast` number, since 1 + 8 + 3 + 9 + 7 + 638 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 18397593 and 18397602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18397637) 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, 44778 + ... + 45186.

It is an arithmetic number, because the mean of its divisors is an integer number (525825).

Almost surely, 2^18397638 is an apocalyptic number.

18397638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18397638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25239600).

18397638 is an abundant number, since it is smaller than the sum of its proper divisors (32081562).

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

18397638 is a wasteful number, since it uses less digits than its factorization.

18397638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451 (or 438 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 18397638 is about 4289.2467870245. The cubic root of 18397638 is about 263.9899273016.

The spelling of 18397638 in words is "eighteen million, three hundred ninety-seven thousand, six hundred thirty-eight".