643936 has 12 divisors (see below), whose sum is σ = 1267812. Its totient is φ = 321952.

The previous prime is 643927. The next prime is 643949. The reversal of 643936 is 639346.

It is a junction number, because it is equal to n+sod(n) for n = 643898 and 643907.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10030 + ... + 10093.

It is an arithmetic number, because the mean of its divisors is an integer number (105651).

2⁶⁴³⁹³⁶ is an apocalyptic number.

It is an amenable number.

643936 is a deficient number, since it is larger than the sum of its proper divisors (623876).

643936 is a wasteful number, since it uses less digits than its factorization.

643936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20133 (or 20125 counting only the distinct ones).

The product of its digits is 11664, while the sum is 31.

The square root of 643936 is about 802.4562293359. The cubic root of 643936 is about 86.3536903177.

The spelling of 643936 in words is "six hundred forty-three thousand, nine hundred thirty-six".