15645 has 16 divisors (see below), whose sum is σ = 28800. Its totient is φ = 7104.

The previous prime is 15643. The next prime is 15647. The reversal of 15645 is 54651.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (15643) and next prime (15647).

It is not a de Polignac number, because 15645 - 2¹ = 15643 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

15645 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15641) 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, 31 + ... + 179.

It is an arithmetic number, because the mean of its divisors is an integer number (1800).

15645 is a Friedman number, since it can be written as 5^6+5*4*1, using all its digits and the basic arithmetic operations.

2¹⁵⁶⁴⁵ is an apocalyptic number.

15645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

15645 is a deficient number, since it is larger than the sum of its proper divisors (13155).

15645 is a wasteful number, since it uses less digits than its factorization.

15645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164.

The product of its digits is 600, while the sum is 21.

The square root of 15645 is about 125.0799744164. The cubic root of 15645 is about 25.0106621188.

The spelling of 15645 in words is "fifteen thousand, six hundred forty-five".