18321817680 has 200 divisors, whose sum is σ = 64351405800. Its totient is φ = 4830769152.

The previous prime is 18321817663. The next prime is 18321817681. The reversal of 18321817680 is 8671812381.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 18974736 + 18302842944 = 4356^2 + 135288^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18321817681) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 560836 + ... + 592604.

It is an arithmetic number, because the mean of its divisors is an integer number (321757029).

Almost surely, 2^18321817680 is an apocalyptic number.

18321817680 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 18321817680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32175702900).

18321817680 is an abundant number, since it is smaller than the sum of its proper divisors (46029588120).

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

18321817680 is a wasteful number, since it uses less digits than its factorization.

18321817680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31883 (or 31868 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The spelling of 18321817680 in words is "eighteen billion, three hundred twenty-one million, eight hundred seventeen thousand, six hundred eighty".