181681840 has 40 divisors (see below), whose sum is σ = 433833840. Its totient is φ = 70707456.

The previous prime is 181681811. The next prime is 181681847. The reversal of 181681840 is 48186181.

181681840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a self number, because there is not a number n which added to its sum of digits gives 181681840.

It is not an unprimeable number, because it can be changed into a prime (181681847) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27730 + ... + 33649.

It is an arithmetic number, because the mean of its divisors is an integer number (10845846).

Almost surely, 2^181681840 is an apocalyptic number.

181681840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

181681840 is an abundant number, since it is smaller than the sum of its proper divisors (252152000).

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

181681840 is a wasteful number, since it uses less digits than its factorization.

181681840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61429 (or 61423 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 37.

The square root of 181681840 is about 13478.9406111905. The cubic root of 181681840 is about 566.3746931089.

The spelling of 181681840 in words is "one hundred eighty-one million, six hundred eighty-one thousand, eight hundred forty".