18644021500 has 96 divisors (see below), whose sum is σ = 44122268736. Its totient is φ = 6841324800.

The previous prime is 18644021477. The next prime is 18644021503. The reversal of 18644021500 is 512044681.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18644021503) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 1050702 + ... + 1068298.

It is an arithmetic number, because the mean of its divisors is an integer number (459606966).

Almost surely, 2^18644021500 is an apocalyptic number.

18644021500 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 18644021500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22061134368).

18644021500 is an abundant number, since it is smaller than the sum of its proper divisors (25478247236).

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

18644021500 is a wasteful number, since it uses less digits than its factorization.

18644021500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17792 (or 17780 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 31.

The spelling of 18644021500 in words is "eighteen billion, six hundred forty-four million, twenty-one thousand, five hundred".