643839 has 32 divisors (see below), whose sum is σ = 1081344. Its totient is φ = 332640.

The previous prime is 643781. The next prime is 643847. The reversal of 643839 is 938346.

643839 = T₁₁₂ + T₁₁₃ + ... + T₁₇₃.

It is not a de Polignac number, because 643839 - 2⁸ = 643583 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643849) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14952 + ... + 14994.

It is an arithmetic number, because the mean of its divisors is an integer number (33792).

2⁶⁴³⁸³⁹ is an apocalyptic number.

643839 is a gapful number since it is divisible by the number (69) formed by its first and last digit.

643839 is a deficient number, since it is larger than the sum of its proper divisors (437505).

643839 is a wasteful number, since it uses less digits than its factorization.

643839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107.

The product of its digits is 15552, while the sum is 33.

The square root of 643839 is about 802.3957876260. The cubic root of 643839 is about 86.3493541059.

The spelling of 643839 in words is "six hundred forty-three thousand, eight hundred thirty-nine".