21224760 has 64 divisors (see below), whose sum is σ = 64471680. Its totient is φ = 5589120.

The previous prime is 21224759. The next prime is 21224761. The reversal of 21224760 is 6742212.

It is an interprime number because it is at equal distance from previous prime (21224759) and next prime (21224761).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21224760.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8895 + ... + 11025.

It is an arithmetic number, because the mean of its divisors is an integer number (1007370).

Almost surely, 2^21224760 is an apocalyptic number.

21224760 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 21224760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32235840).

21224760 is an abundant number, since it is smaller than the sum of its proper divisors (43246920).

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

21224760 is a wasteful number, since it uses less digits than its factorization.

21224760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2228 (or 2224 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 21224760 is about 4607.0337528609. The cubic root of 21224760 is about 276.8732058816.

Adding to 21224760 its reverse (6742212), we get a palindrome (27966972).

The spelling of 21224760 in words is "twenty-one million, two hundred twenty-four thousand, seven hundred sixty".