181221830 has 32 divisors (see below), whose sum is σ = 341280000. Its totient is φ = 69154272.

The previous prime is 181221811. The next prime is 181221847. The reversal of 181221830 is 38122181.

It is a self number, because there is not a number n which added to its sum of digits gives 181221830.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 113981 + ... + 115559.

It is an arithmetic number, because the mean of its divisors is an integer number (10665000).

Almost surely, 2^181221830 is an apocalyptic number.

181221830 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

181221830 is a deficient number, since it is larger than the sum of its proper divisors (160058170).

181221830 is a wasteful number, since it uses less digits than its factorization.

181221830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2108.

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 181221830 is about 13461.8657696472. The cubic root of 181221830 is about 565.8962776135.

The spelling of 181221830 in words is "one hundred eighty-one million, two hundred twenty-one thousand, eight hundred thirty".