3645 has 14 divisors (see below), whose sum is σ = 6558. Its totient is φ = 1944.

The previous prime is 3643. The next prime is 3659. The reversal of 3645 is 5463.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 2916 + 729 = 54^2 + 27^2 .

It is not a de Polignac number, because 3645 - 2¹ = 3643 is a prime.

Its product of digits (360) is a multiple of the sum of its prime divisors (8).

It is a nialpdrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3643) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 727 + ... + 731.

2³⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

3645 is a deficient number, since it is larger than the sum of its proper divisors (2913).

3645 is an frugal number, since it uses more digits than its factorization.

3645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23 (or 8 counting only the distinct ones).

The product of its digits is 360, while the sum is 18.

The square root of 3645 is about 60.3738353925. The cubic root of 3645 is about 15.3897835201.

Adding to 3645 its sum of digits (18), we get a palindrome (3663).

Adding to 3645 its product of digits (360), we get a triangular number (4005 = T₈₉).

It can be divided in two parts, 36 and 45, that added together give a 4-th power (81 = 3⁴).

The spelling of 3645 in words is "three thousand, six hundred forty-five".