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21288960 = 211335711

21288960 has 384 divisors, whose sum is σ = 94348800. Its totient is φ = 4423680.

The previous prime is 21288959. The next prime is 21288973. The reversal of 21288960 is 6988212.

Adding to 21288960 its sum of digits (36), we get a square (21288996 = 46142).

21288960 divided by its product of nonzero digits (13824) gives a triangular number (1540 = T55).

It is a tau number, because it is divible by the number of its divisors (384).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1935355 + ... + 1935365.

It is an arithmetic number, because the mean of its divisors is an integer number (245700).

Almost surely, 221288960 is an apocalyptic number.

21288960 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 21288960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47174400).

21288960 is an abundant number, since it is smaller than the sum of its proper divisors (73059840).

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

21288960 is a wasteful number, since it uses less digits than its factorization.

21288960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54 (or 28 counting only the distinct ones).

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

The square root of 21288960 is about 4613.9960988280. The cubic root of 21288960 is about 277.1520840700.

The spelling of 21288960 in words is "twenty-one million, two hundred eighty-eight thousand, nine hundred sixty".