181521000000 has 784 divisors, whose sum is σ = 683410002240. Its totient is φ = 47822400000.

The previous prime is 181520999987. The next prime is 181521000007. The reversal of 181521000000 is 125181.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (181521000007) 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 111 ways as a sum of consecutive naturals, for example, 2186999959 + ... + 2187000041.

Almost surely, 2^181521000000 is an apocalyptic number.

181521000000 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 181521000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (341705001120).

181521000000 is an abundant number, since it is smaller than the sum of its proper divisors (501889002240).

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

181521000000 is an frugal number, since it uses more digits than its factorization.

181521000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146 (or 93 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

Adding to 181521000000 its reverse (125181), we get a palindrome (181521125181).

The spelling of 181521000000 in words is "one hundred eighty-one billion, five hundred twenty-one million", and thus it is an aban number.