213861 has 4 divisors (see below), whose sum is σ = 285152. Its totient is φ = 142572.

The previous prime is 213859. The next prime is 213881. The reversal of 213861 is 168312.

213861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 213861 - 2¹ = 213859 is a prime.

It is an Ulam number.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 213861.

It is not an unprimeable number, because it can be changed into a prime (213821) 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, 35641 + ... + 35646.

It is an arithmetic number, because the mean of its divisors is an integer number (71288).

2²¹³⁸⁶¹ is an apocalyptic number.

It is an amenable number.

213861 is a deficient number, since it is larger than the sum of its proper divisors (71291).

213861 is an equidigital number, since it uses as much as digits as its factorization.

213861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71290.

The product of its digits is 288, while the sum is 21.

The square root of 213861 is about 462.4510784937. The cubic root of 213861 is about 59.8012870571.

The spelling of 213861 in words is "two hundred thirteen thousand, eight hundred sixty-one".