215643 has 4 divisors (see below), whose sum is σ = 287528. Its totient is φ = 143760.

The previous prime is 215617. The next prime is 215653. The reversal of 215643 is 346512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 215643 - 2¹⁶ = 150107 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215653) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35938 + ... + 35943.

It is an arithmetic number, because the mean of its divisors is an integer number (71882).

2²¹⁵⁶⁴³ is an apocalyptic number.

215643 is a deficient number, since it is larger than the sum of its proper divisors (71885).

215643 is an equidigital number, since it uses as much as digits as its factorization.

215643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71884.

The product of its digits is 720, while the sum is 21.

The square root of 215643 is about 464.3737718692. The cubic root of 215643 is about 59.9669262165.

It can be divided in two parts, 215 and 643, that added together give a palindrome (858).

The spelling of 215643 in words is "two hundred fifteen thousand, six hundred forty-three".