21280896 has 288 divisors, whose sum is σ = 79361100. Its totient is φ = 5419008.

The previous prime is 21280891. The next prime is 21280907. The reversal of 21280896 is 69808212.

It can be written as a sum of positive squares in 2 ways, for example, as 20575296 + 705600 = 4536^2 + 840^2 .

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21280896.

It is not an unprimeable number, because it can be changed into a prime (21280891) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 733810 + ... + 733838.

Almost surely, 2^21280896 is an apocalyptic number.

21280896 is a gapful number since it is divisible by the number (26) 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 21280896, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39680550).

21280896 is an abundant number, since it is smaller than the sum of its proper divisors (58080204).

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

21280896 is a wasteful number, since it uses less digits than its factorization.

21280896 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 21280896 is about 4613.1221531626. The cubic root of 21280896 is about 277.1170857006.

The spelling of 21280896 in words is "twenty-one million, two hundred eighty thousand, eight hundred ninety-six".