639433 has 2 divisors, whose sum is σ = 639434. Its totient is φ = 639432.

The previous prime is 639391. The next prime is 639439. The reversal of 639433 is 334936.

639433 is nontrivially palindromic in base 16.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 356409 + 283024 = 597^2 + 532^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639433 is a prime.

It is a super-2 number, since 2×639433² = 817749122978, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639439) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319716 + 319717.

It is an arithmetic number, because the mean of its divisors is an integer number (319717).

2⁶³⁹⁴³³ is an apocalyptic number.

It is an amenable number.

639433 is a deficient number, since it is larger than the sum of its proper divisors (1).

639433 is an equidigital number, since it uses as much as digits as its factorization.

639433 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5832, while the sum is 28.

The square root of 639433 is about 799.6455464767. The cubic root of 639433 is about 86.1519308223.

The spelling of 639433 in words is "six hundred thirty-nine thousand, four hundred thirty-three".