231639 has 4 divisors (see below), whose sum is σ = 308856. Its totient is φ = 154424.

The previous prime is 231631. The next prime is 231643. The reversal of 231639 is 936132.

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 231639 - 2³ = 231631 is a prime.

It is a D-number.

231639 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231631) 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, 38604 + ... + 38609.

It is an arithmetic number, because the mean of its divisors is an integer number (77214).

2²³¹⁶³⁹ is an apocalyptic number.

231639 is a deficient number, since it is larger than the sum of its proper divisors (77217).

231639 is an equidigital number, since it uses as much as digits as its factorization.

231639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77216.

The product of its digits is 972, while the sum is 24.

The square root of 231639 is about 481.2888945322. The cubic root of 231639 is about 61.4144490959.

The spelling of 231639 in words is "two hundred thirty-one thousand, six hundred thirty-nine".