209638 has 16 divisors (see below), whose sum is σ = 369936. Its totient is φ = 87840.

The previous prime is 209623. The next prime is 209639. The reversal of 209638 is 836902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209639) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81 + ... + 652.

It is an arithmetic number, because the mean of its divisors is an integer number (23121).

2²⁰⁹⁶³⁸ is an apocalyptic number.

209638 is a deficient number, since it is larger than the sum of its proper divisors (160298).

209638 is a wasteful number, since it uses less digits than its factorization.

209638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 759.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 209638 is about 457.8624247522. The cubic root of 209638 is about 59.4050459196.

Subtracting from 209638 its product of nonzero digits (2592), we obtain a triangular number (207046 = T₆₄₃).

Subtracting 209638 from its reverse (836902), we obtain a square (627264 = 792²).

The spelling of 209638 in words is "two hundred nine thousand, six hundred thirty-eight".