21170 has 16 divisors (see below), whose sum is σ = 39960. Its totient is φ = 8064.

The previous prime is 21169. The next prime is 21179. The reversal of 21170 is 7112.

21170 = 83² + 84² + 85².

It can be written as a sum of positive squares in 4 ways, for example, as 17689 + 3481 = 133^2 + 59^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21179) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 254 + ... + 326.

2²¹¹⁷⁰ is an apocalyptic number.

It is a pronic number, being equal to 145×146.

21170 is a deficient number, since it is larger than the sum of its proper divisors (18790).

21170 is a wasteful number, since it uses less digits than its factorization.

21170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109.

The product of its (nonzero) digits is 14, while the sum is 11.

The square root of 21170 is about 145.4991408909. The cubic root of 21170 is about 27.6634889336.

Adding to 21170 its reverse (7112), we get a palindrome (28282).

It can be divided in two parts, 21 and 170, that multiplied together give a triangular number (3570 = T₈₄).

The spelling of 21170 in words is "twenty-one thousand, one hundred seventy", and thus it is an iban number.