21160720 has 80 divisors (see below), whose sum is σ = 58210560. Its totient is φ = 6999552.

The previous prime is 21160709. The next prime is 21160721. The reversal of 21160720 is 2706112.

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (21160721) 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, 15589 + ... + 16891.

It is an arithmetic number, because the mean of its divisors is an integer number (727632).

Almost surely, 2^21160720 is an apocalyptic number.

21160720 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 21160720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29105280).

21160720 is an abundant number, since it is smaller than the sum of its proper divisors (37049840).

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

21160720 is a wasteful number, since it uses less digits than its factorization.

21160720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1352 (or 1346 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21160720 is about 4600.0782602038. The cubic root of 21160720 is about 276.5944618917.

Adding to 21160720 its reverse (2706112), we get a palindrome (23866832).

The spelling of 21160720 in words is "twenty-one million, one hundred sixty thousand, seven hundred twenty".