21804180 has 24 divisors (see below), whose sum is σ = 61051872. Its totient is φ = 5814432.

The previous prime is 21804179. The next prime is 21804187. The reversal of 21804180 is 8140812.

It is a self number, because there is not a number n which added to its sum of digits gives 21804180.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21804187) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 181642 + ... + 181761.

It is an arithmetic number, because the mean of its divisors is an integer number (2543828).

Almost surely, 2^21804180 is an apocalyptic number.

21804180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21804180 is an abundant number, since it is smaller than the sum of its proper divisors (39247692).

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

21804180 is a wasteful number, since it uses less digits than its factorization.

21804180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363415 (or 363413 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21804180 is about 4669.4946193352. The cubic root of 21804180 is about 279.3700976073.

Adding to 21804180 its reverse (8140812), we get a palindrome (29944992).

The spelling of 21804180 in words is "twenty-one million, eight hundred four thousand, one hundred eighty".