281639 has 4 divisors (see below), whose sum is σ = 298224. Its totient is φ = 265056.

The previous prime is 281627. The next prime is 281641. The reversal of 281639 is 936182.

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

It is a cyclic number.

It is not a de Polignac number, because 281639 - 2⁴ = 281623 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (281609) 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, 8267 + ... + 8300.

It is an arithmetic number, because the mean of its divisors is an integer number (74556).

2²⁸¹⁶³⁹ is an apocalyptic number.

281639 is a deficient number, since it is larger than the sum of its proper divisors (16585).

281639 is a wasteful number, since it uses less digits than its factorization.

281639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16584.

The product of its digits is 2592, while the sum is 29.

The square root of 281639 is about 530.6967118798. The cubic root of 281639 is about 65.5487274108.

The spelling of 281639 in words is "two hundred eighty-one thousand, six hundred thirty-nine".