21053760 has 224 divisors, whose sum is σ = 82612992. Its totient is φ = 4423680.

The previous prime is 21053741. The next prime is 21053783. The reversal of 21053760 is 6735012.

It is a tau number, because it is divible by the number of its divisors (224).

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

It is a zygodrome in base 4.

It is a self number, because there is not a number n which added to its sum of digits gives 21053760.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 87240 + ... + 87480.

It is an arithmetic number, because the mean of its divisors is an integer number (368808).

Almost surely, 2^21053760 is an apocalyptic number.

21053760 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 21053760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41306496).

21053760 is an abundant number, since it is smaller than the sum of its proper divisors (61559232).

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

21053760 is a wasteful number, since it uses less digits than its factorization.

21053760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281 (or 271 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 24.

The square root of 21053760 is about 4588.4376425969. The cubic root of 21053760 is about 276.1276452210.

Adding to 21053760 its reverse (6735012), we get a palindrome (27788772).

It can be divided in two parts, 210 and 53760, that multiplied together give a square (11289600 = 3360²).

The spelling of 21053760 in words is "twenty-one million, fifty-three thousand, seven hundred sixty".