21718180 has 48 divisors (see below), whose sum is σ = 52690176. Its totient is φ = 7431680.

The previous prime is 21718133. The next prime is 21718189. The reversal of 21718180 is 8181712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21718189) 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 15 ways as a sum of consecutive naturals, for example, 837 + ... + 6643.

It is an arithmetic number, because the mean of its divisors is an integer number (1097712).

Almost surely, 2^21718180 is an apocalyptic number.

21718180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21718180, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26345088).

21718180 is an abundant number, since it is smaller than the sum of its proper divisors (30971996).

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

21718180 is a wasteful number, since it uses less digits than its factorization.

21718180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5844 (or 5842 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 21718180 is about 4660.2768158126. The cubic root of 21718180 is about 279.0023166691.

Adding to 21718180 its reverse (8181712), we get a palindrome (29899892).

It can be divided in two parts, 21 and 718180, that added together give a triangular number (718201 = T₁₁₉₈).

The spelling of 21718180 in words is "twenty-one million, seven hundred eighteen thousand, one hundred eighty".