20145 has 16 divisors (see below), whose sum is σ = 34560. Its totient is φ = 9984.

The previous prime is 20143. The next prime is 20147. The reversal of 20145 is 54102.

20145 = T₁₆ + T₁₇ + ... + T₄₉.

20145 is nontrivially palindromic in base 4.

20145 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (20143) and next prime (20147).

It is not a de Polignac number, because 20145 - 2¹ = 20143 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20145.

It is not an unprimeable number, because it can be changed into a prime (20143) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 216 + ... + 294.

It is an arithmetic number, because the mean of its divisors is an integer number (2160).

2²⁰¹⁴⁵ is an apocalyptic number.

It is an amenable number.

20145 is a deficient number, since it is larger than the sum of its proper divisors (14415).

20145 is a wasteful number, since it uses less digits than its factorization.

20145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104.

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 20145 is about 141.9330828243. The cubic root of 20145 is about 27.2096166976.

Adding to 20145 its reverse (54102), we get a palindrome (74247).

It can be divided in two parts, 201 and 45, that multiplied together give a triangular number (9045 = T₁₃₄).

The spelling of 20145 in words is "twenty thousand, one hundred forty-five".