21717160 has 64 divisors (see below), whose sum is σ = 52390800. Its totient is φ = 8073216.

The previous prime is 21717139. The next prime is 21717161. The reversal of 21717160 is 6171712.

It can be written as a sum of positive squares in 8 ways, for example, as 19412836 + 2304324 = 4406^2 + 1518^2 .

It is not an unprimeable number, because it can be changed into a prime (21717161) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73974 + ... + 74266.

Almost surely, 2^21717160 is an apocalyptic number.

21717160 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 21717160, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26195400).

21717160 is an abundant number, since it is smaller than the sum of its proper divisors (30673640).

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

21717160 is a wasteful number, since it uses less digits than its factorization.

21717160 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430 (or 426 counting only the distinct ones).

The product of its (nonzero) digits is 588, while the sum is 25.

The square root of 21717160 is about 4660.1673789683. The cubic root of 21717160 is about 278.9979487951.

Adding to 21717160 its reverse (6171712), we get a palindrome (27888872).

The spelling of 21717160 in words is "twenty-one million, seven hundred seventeen thousand, one hundred sixty".