21263760 has 120 divisors (see below), whose sum is σ = 81631680. Its totient is φ = 4859136.

The previous prime is 21263743. The next prime is 21263761. The reversal of 21263760 is 6736212.

It is a happy number.

21263760 is a `hidden beast` number, since 21 + 2 + 637 + 6 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

It is not an unprimeable number, because it can be changed into a prime (21263761) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2931 + ... + 7149.

It is an arithmetic number, because the mean of its divisors is an integer number (680264).

Almost surely, 2^21263760 is an apocalyptic number.

21263760 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 21263760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40815840).

21263760 is an abundant number, since it is smaller than the sum of its proper divisors (60367920).

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

21263760 is a wasteful number, since it uses less digits than its factorization.

21263760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4245 (or 4236 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 27.

The square root of 21263760 is about 4611.2644686680. The cubic root of 21263760 is about 277.0426847991.

Adding to 21263760 its reverse (6736212), we get a palindrome (27999972).

It can be divided in two parts, 2126 and 3760, that added together give a triangular number (5886 = T₁₀₈).

The spelling of 21263760 in words is "twenty-one million, two hundred sixty-three thousand, seven hundred sixty".