181918420 has 24 divisors (see below), whose sum is σ = 382339944. Its totient is φ = 72708096.

The previous prime is 181918397. The next prime is 181918427. The reversal of 181918420 is 24819181.

It can be written as a sum of positive squares in 4 ways, for example, as 23309584 + 158608836 = 4828^2 + 12594^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181918427) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 28132 + ... + 33988.

It is an arithmetic number, because the mean of its divisors is an integer number (15930831).

Almost surely, 2^181918420 is an apocalyptic number.

181918420 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

181918420 is an abundant number, since it is smaller than the sum of its proper divisors (200421524).

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

181918420 is a wasteful number, since it uses less digits than its factorization.

181918420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7419 (or 7417 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 34.

The square root of 181918420 is about 13487.7136683724. The cubic root of 181918420 is about 566.6204245234.

The spelling of 181918420 in words is "one hundred eighty-one million, nine hundred eighteen thousand, four hundred twenty".