643959 has 6 divisors (see below), whose sum is σ = 930176. Its totient is φ = 429300.

The previous prime is 643957. The next prime is 643961. The reversal of 643959 is 959346.

643959 is a `hidden beast` number, since 643 + 9 + 5 + 9 = 666.

It is an interprime number because it is at equal distance from previous prime (643957) and next prime (643961).

It is not a de Polignac number, because 643959 - 2¹ = 643957 is a prime.

It is a Duffinian 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 pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35767 + ... + 35784.

2⁶⁴³⁹⁵⁹ is an apocalyptic number.

643959 is a deficient number, since it is larger than the sum of its proper divisors (286217).

643959 is a wasteful number, since it uses less digits than its factorization.

643959 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71557 (or 71554 counting only the distinct ones).

The product of its digits is 29160, while the sum is 36.

The square root of 643959 is about 802.4705602077. The cubic root of 643959 is about 86.3547184278.

The spelling of 643959 in words is "six hundred forty-three thousand, nine hundred fifty-nine".