20172 has 18 divisors (see below), whose sum is σ = 48244. Its totient is φ = 6560.

The previous prime is 20161. The next prime is 20173. The reversal of 20172 is 27102.

20172 is nontrivially palindromic in base 9.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an Ulam number.

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (20173) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 472 + ... + 512.

2²⁰¹⁷² is an apocalyptic number.

It is an amenable number.

20172 is an abundant number, since it is smaller than the sum of its proper divisors (28072).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24122).

20172 is a wasteful number, since it uses less digits than its factorization.

20172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 12.

The square root of 20172 is about 142.0281662206. The cubic root of 20172 is about 27.2217674658.

Multiplying 20172 by its sum of digits (12), we get a square (242064 = 492²).

20172 divided by its sum of digits (12) gives a square (1681 = 41²).

Adding to 20172 its reverse (27102), we get a palindrome (47274).

The spelling of 20172 in words is "twenty thousand, one hundred seventy-two", and thus it is an iban number.