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21088 = 25659

21088 has 12 divisors (see below), whose sum is σ = 41580. Its totient is φ = 10528.

The previous prime is 21067. The next prime is 21089. The reversal of 21088 is 88012.

It is a happy number.

21088 is nontrivially palindromic in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 298 + ... + 361.

It is an arithmetic number, because the mean of its divisors is an integer number (3465).

221088 is an apocalyptic number.

It is an amenable number.

21088 is a deficient number, since it is larger than the sum of its proper divisors (20492).

21088 is an equidigital number, since it uses as much as digits as its factorization.

21088 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 669 (or 661 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 21088 is about 145.2170788854. The cubic root of 21088 is about 27.6277254124.

It can be divided in two parts, 2108 and 8, that added together give a square (2116 = 462).

The spelling of 21088 in words is "twenty-one thousand, eighty-eight".

Divisors: 1 2 4 8 16 32 659 1318 2636 5272 10544 21088