21717080 has 96 divisors (see below), whose sum is σ = 61477920. Its totient is φ = 6758400.

The previous prime is 21717071. The next prime is 21717089. The reversal of 21717080 is 8071712.

It is an interprime number because it is at equal distance from previous prime (21717071) and next prime (21717089).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21717089) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33560 + ... + 34200.

It is an arithmetic number, because the mean of its divisors is an integer number (640395).

Almost surely, 2^21717080 is an apocalyptic number.

21717080 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 21717080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30738960).

21717080 is an abundant number, since it is smaller than the sum of its proper divisors (39760840).

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

21717080 is a wasteful number, since it uses less digits than its factorization.

21717080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681 (or 666 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 26.

The square root of 21717080 is about 4660.1587955777. The cubic root of 21717080 is about 278.9976062110.

Adding to 21717080 its reverse (8071712), we get a palindrome (29788792).

The spelling of 21717080 in words is "twenty-one million, seven hundred seventeen thousand, eighty".