181609213440 has 640 divisors, whose sum is σ = 620690273280. Its totient is φ = 45234782208.

The previous prime is 181609213439. The next prime is 181609213447. The reversal of 181609213440 is 44312906181.

It is a tau number, because it is divible by the number of its divisors (640).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181609213447) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1087480237 + ... + 1087480403.

It is an arithmetic number, because the mean of its divisors is an integer number (969828552).

Almost surely, 2^181609213440 is an apocalyptic number.

181609213440 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 181609213440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (310345136640).

181609213440 is an abundant number, since it is smaller than the sum of its proper divisors (439081059840).

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

181609213440 is a wasteful number, since it uses less digits than its factorization.

181609213440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362 (or 346 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 39.

The spelling of 181609213440 in words is "one hundred eighty-one billion, six hundred nine million, two hundred thirteen thousand, four hundred forty".