21100560 has 80 divisors (see below), whose sum is σ = 70453824. Its totient is φ = 5193216.

The previous prime is 21100559. The next prime is 21100579. The reversal of 21100560 is 6500112.

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

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 262 + ... + 6501.

Almost surely, 2^21100560 is an apocalyptic number.

21100560 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 21100560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35226912).

21100560 is an abundant number, since it is smaller than the sum of its proper divisors (49353264).

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

21100560 is a wasteful number, since it uses less digits than its factorization.

21100560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6792 (or 6786 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21100560 is about 4593.5345867861. The cubic root of 21100560 is about 276.3320934263.

Adding to 21100560 its reverse (6500112), we get a palindrome (27600672).

The spelling of 21100560 in words is "twenty-one million, one hundred thousand, five hundred sixty".