211638 has 16 divisors (see below), whose sum is σ = 483840. Its totient is φ = 60456.

The previous prime is 211619. The next prime is 211639. The reversal of 211638 is 836112.

211638 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2478 + ... + 2561.

It is an arithmetic number, because the mean of its divisors is an integer number (30240).

2²¹¹⁶³⁸ is an apocalyptic number.

211638 is an abundant number, since it is smaller than the sum of its proper divisors (272202).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

211638 is a wasteful number, since it uses less digits than its factorization.

211638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5051.

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

The square root of 211638 is about 460.0413024936. The cubic root of 211638 is about 59.5933614214.

It can be divided in two parts, 2116 and 38, that multiplied together give a palindrome (80408).

The spelling of 211638 in words is "two hundred eleven thousand, six hundred thirty-eight".