181138220 has 48 divisors (see below), whose sum is σ = 386019648. Its totient is φ = 71393280.

The previous prime is 181138183. The next prime is 181138261. The reversal of 181138220 is 22831181.

It is a super-2 number, since 2×181138220² = 65622109489536800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 181138220.

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, 644480 + ... + 644760.

It is an arithmetic number, because the mean of its divisors is an integer number (8042076).

Almost surely, 2^181138220 is an apocalyptic number.

181138220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

181138220 is an abundant number, since it is smaller than the sum of its proper divisors (204881428).

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

181138220 is a wasteful number, since it uses less digits than its factorization.

181138220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 650 (or 648 counting only the distinct ones).

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

The square root of 181138220 is about 13458.7599725978. The cubic root of 181138220 is about 565.8092353660.

The spelling of 181138220 in words is "one hundred eighty-one million, one hundred thirty-eight thousand, two hundred twenty".