181321816 has 32 divisors (see below), whose sum is σ = 368953200. Its totient is φ = 83041920.

The previous prime is 181321801. The next prime is 181321823. The reversal of 181321816 is 618123181.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6970 + ... + 20278.

Almost surely, 2^181321816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 181321816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (184476600).

181321816 is an abundant number, since it is smaller than the sum of its proper divisors (187631384).

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

181321816 is a wasteful number, since it uses less digits than its factorization.

181321816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13459 (or 13455 counting only the distinct ones).

The product of its digits is 2304, while the sum is 31.

The square root of 181321816 is about 13465.5789329683. The cubic root of 181321816 is about 566.0003329627. Note that the first 3 decimals are identical.

Adding to 181321816 its reverse (618123181), we get a palindrome (799444997).

The spelling of 181321816 in words is "one hundred eighty-one million, three hundred twenty-one thousand, eight hundred sixteen".