643958 has 12 divisors (see below), whose sum is σ = 1123812. Its totient is φ = 275940.

The previous prime is 643957. The next prime is 643961. The reversal of 643958 is 859346.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643957) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3188 + ... + 3383.

It is an arithmetic number, because the mean of its divisors is an integer number (93651).

2⁶⁴³⁹⁵⁸ is an apocalyptic number.

643958 is a deficient number, since it is larger than the sum of its proper divisors (479854).

643958 is a wasteful number, since it uses less digits than its factorization.

643958 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6587 (or 6580 counting only the distinct ones).

The product of its digits is 25920, while the sum is 35.

The square root of 643958 is about 802.4699371316. The cubic root of 643958 is about 86.3546737278.

The spelling of 643958 in words is "six hundred forty-three thousand, nine hundred fifty-eight".