643879 has 2 divisors, whose sum is σ = 643880. Its totient is φ = 643878.

The previous prime is 643873. The next prime is 643883. The reversal of 643879 is 978346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643879 - 2⁵ = 643847 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643873) 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 as a sum of consecutive naturals, namely, 321939 + 321940.

It is an arithmetic number, because the mean of its divisors is an integer number (321940).

2⁶⁴³⁸⁷⁹ is an apocalyptic number.

643879 is a deficient number, since it is larger than the sum of its proper divisors (1).

643879 is an equidigital number, since it uses as much as digits as its factorization.

643879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 37.

The square root of 643879 is about 802.4207125941. The cubic root of 643879 is about 86.3511422873.

The spelling of 643879 in words is "six hundred forty-three thousand, eight hundred seventy-nine".