21768180 has 48 divisors (see below), whose sum is σ = 69659520. Its totient is φ = 4975488.

The previous prime is 21768179. The next prime is 21768199. The reversal of 21768180 is 8186712.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 25495 + ... + 26334.

It is an arithmetic number, because the mean of its divisors is an integer number (1451240).

Almost surely, 2^21768180 is an apocalyptic number.

21768180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21768180 is an abundant number, since it is smaller than the sum of its proper divisors (47891340).

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

21768180 is a wasteful number, since it uses less digits than its factorization.

21768180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51848 (or 51846 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 33.

The square root of 21768180 is about 4665.6382200081. The cubic root of 21768180 is about 279.2162606874.

The spelling of 21768180 in words is "twenty-one million, seven hundred sixty-eight thousand, one hundred eighty".