21172 has 12 divisors (see below), whose sum is σ = 38080. Its totient is φ = 10296.

The previous prime is 21169. The next prime is 21179. The reversal of 21172 is 27112.

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 3 ways as a sum of consecutive naturals, for example, 229 + ... + 307.

2²¹¹⁷² is an apocalyptic number.

It is an amenable number.

21172 is a deficient number, since it is larger than the sum of its proper divisors (16908).

21172 is a wasteful number, since it uses less digits than its factorization.

21172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150 (or 148 counting only the distinct ones).

The product of its digits is 28, while the sum is 13.

The square root of 21172 is about 145.5060136214. The cubic root of 21172 is about 27.6643600600.

Adding to 21172 its reverse (27112), we get a palindrome (48284).

The spelling of 21172 in words is "twenty-one thousand, one hundred seventy-two", and thus it is an iban number.