181220040 has 48 divisors (see below), whose sum is σ = 588966300. Its totient is φ = 48325248.

The previous prime is 181220033. The next prime is 181220047. The reversal of 181220040 is 40022181.

It is an interprime number because it is at equal distance from previous prime (181220033) and next prime (181220047).

It can be written as a sum of positive squares in 2 ways, for example, as 159820164 + 21399876 = 12642^2 + 4626^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 181219995 and 181220022.

It is not an unprimeable number, because it can be changed into a prime (181220047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 251335 + ... + 252054.

Almost surely, 2^181220040 is an apocalyptic number.

181220040 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

181220040 is an abundant number, since it is smaller than the sum of its proper divisors (407746260).

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

181220040 is a wasteful number, since it uses less digits than its factorization.

181220040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503406 (or 503399 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 181220040 is about 13461.7992853853. The cubic root of 181220040 is about 565.8944144133.

The spelling of 181220040 in words is "one hundred eighty-one million, two hundred twenty thousand, forty".