18438999390 has 144 divisors (see below), whose sum is σ = 56104749792. Its totient is φ = 4189223808.

The previous prime is 18438999373. The next prime is 18438999427. The reversal of 18438999390 is 9399983481.

It is a happy number.

18438999390 is a `hidden beast` number, since 1 + 84 + 3 + 89 + 99 + 390 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 723952 + ... + 748988.

It is an arithmetic number, because the mean of its divisors is an integer number (389616318).

Almost surely, 2^18438999390 is an apocalyptic number.

18438999390 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18438999390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28052374896).

18438999390 is an abundant number, since it is smaller than the sum of its proper divisors (37665750402).

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

18438999390 is a wasteful number, since it uses less digits than its factorization.

18438999390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25231 (or 25221 counting only the distinct ones).

The product of its (nonzero) digits is 15116544, while the sum is 63.

The spelling of 18438999390 in words is "eighteen billion, four hundred thirty-eight million, nine hundred ninety-nine thousand, three hundred ninety".