642439 has 8 divisors (see below), whose sum is σ = 749600. Its totient is φ = 550368.

The previous prime is 642427. The next prime is 642457. The reversal of 642439 is 934246.

It is not a de Polignac number, because 642439 - 2⁵ = 642407 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642419) 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, 594 + ... + 1279.

It is an arithmetic number, because the mean of its divisors is an integer number (93700).

2⁶⁴²⁴³⁹ is an apocalyptic number.

642439 is a deficient number, since it is larger than the sum of its proper divisors (107161).

642439 is an equidigital number, since it uses as much as digits as its factorization.

642439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1894 (or 1880 counting only the distinct ones).

The product of its digits is 5184, while the sum is 28.

The square root of 642439 is about 801.5229254363. The cubic root of 642439 is about 86.2867210437.

Subtracting from 642439 its sum of digits (28), we obtain a triangular number (642411 = T₁₁₃₃).

It can be divided in two parts, 642 and 439, that added together give a triangular number (1081 = T₄₆).

The spelling of 642439 in words is "six hundred forty-two thousand, four hundred thirty-nine".