181215820 has 12 divisors (see below), whose sum is σ = 380553264. Its totient is φ = 72486320.

The previous prime is 181215773. The next prime is 181215823. The reversal of 181215820 is 28512181.

It is not an unprimeable number, because it can be changed into a prime (181215823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4530376 + ... + 4530415.

It is an arithmetic number, because the mean of its divisors is an integer number (31712772).

Almost surely, 2^181215820 is an apocalyptic number.

181215820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

181215820 is an abundant number, since it is smaller than the sum of its proper divisors (199337444).

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

181215820 is a wasteful number, since it uses less digits than its factorization.

181215820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9060800 (or 9060798 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 28.

The square root of 181215820 is about 13461.6425446526. The cubic root of 181215820 is about 565.8900217921.

The spelling of 181215820 in words is "one hundred eighty-one million, two hundred fifteen thousand, eight hundred twenty".