21718080 has 84 divisors (see below), whose sum is σ = 74711052. Its totient is φ = 5790720.

The previous prime is 21718051. The next prime is 21718087. The reversal of 21718080 is 8081712.

It can be written as a sum of positive squares in 2 ways, for example, as 4875264 + 16842816 = 2208^2 + 4104^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21718087) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 891 + ... + 6650.

Almost surely, 2^21718080 is an apocalyptic number.

21718080 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 21718080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37355526).

21718080 is an abundant number, since it is smaller than the sum of its proper divisors (52992972).

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

21718080 is a wasteful number, since it uses less digits than its factorization.

21718080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7564 (or 7551 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 21718080 is about 4660.2660868238. The cubic root of 21718080 is about 279.0018884522.

Adding to 21718080 its reverse (8081712), we get a palindrome (29799792).

The spelling of 21718080 in words is "twenty-one million, seven hundred eighteen thousand, eighty".