21726180 has 144 divisors (see below), whose sum is σ = 77261184. Its totient is φ = 4838400.

The previous prime is 21726169. The next prime is 21726181. The reversal of 21726180 is 8162712.

It is not an unprimeable number, because it can be changed into a prime (21726181) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 53980 + ... + 54380.

It is an arithmetic number, because the mean of its divisors is an integer number (536536).

Almost surely, 2^21726180 is an apocalyptic number.

21726180 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 21726180, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38630592).

21726180 is an abundant number, since it is smaller than the sum of its proper divisors (55535004).

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

21726180 is a wasteful number, since it uses less digits than its factorization.

21726180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 466 (or 461 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 21726180 is about 4661.1350548981. The cubic root of 21726180 is about 279.0365697623.

Adding to 21726180 its reverse (8162712), we get a palindrome (29888892).

The spelling of 21726180 in words is "twenty-one million, seven hundred twenty-six thousand, one hundred eighty".