181997550 has 96 divisors (see below), whose sum is σ = 573177600. Its totient is φ = 41597280.

The previous prime is 181997549. The next prime is 181997573. The reversal of 181997550 is 55799181.

181997550 is a `hidden beast` number, since 1 + 8 + 1 + 9 + 97 + 550 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a junction number, because it is equal to n+sod(n) for n = 181997496 and 181997505.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 180 + ... + 19079.

It is an arithmetic number, because the mean of its divisors is an integer number (5970600).

Almost surely, 2^181997550 is an apocalyptic number.

181997550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 181997550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (286588800).

181997550 is an abundant number, since it is smaller than the sum of its proper divisors (391180050).

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

181997550 is a wasteful number, since it uses less digits than its factorization.

181997550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19287 (or 19276 counting only the distinct ones).

The product of its (nonzero) digits is 113400, while the sum is 45.

The square root of 181997550 is about 13490.6467598852. The cubic root of 181997550 is about 566.7025678907.

The spelling of 181997550 in words is "one hundred eighty-one million, nine hundred ninety-seven thousand, five hundred fifty".