213561 has 12 divisors (see below), whose sum is σ = 314340. Its totient is φ = 139680.

The previous prime is 213557. The next prime is 213589. The reversal of 213561 is 165312.

It can be written as a sum of positive squares in 2 ways, for example, as 24336 + 189225 = 156^2 + 435^2 .

It is not a de Polignac number, because 213561 - 2² = 213557 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 213561.

It is not an unprimeable number, because it can be changed into a prime (213361) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 355 + ... + 743.

It is an arithmetic number, because the mean of its divisors is an integer number (26195).

2²¹³⁵⁶¹ is an apocalyptic number.

It is an amenable number.

213561 is a deficient number, since it is larger than the sum of its proper divisors (100779).

213561 is a wasteful number, since it uses less digits than its factorization.

213561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 456 (or 453 counting only the distinct ones).

The product of its digits is 180, while the sum is 18.

The square root of 213561 is about 462.1266060291. The cubic root of 213561 is about 59.7733112824.

Adding to 213561 its reverse (165312), we get a palindrome (378873).

The spelling of 213561 in words is "two hundred thirteen thousand, five hundred sixty-one".