640039 has 2 divisors, whose sum is σ = 640040. Its totient is φ = 640038.

The previous prime is 640027. The next prime is 640043. The reversal of 640039 is 930046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640039 - 2⁵ = 640007 is a prime.

640039 is a lucky number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320019 + 320020.

It is an arithmetic number, because the mean of its divisors is an integer number (320020).

2⁶⁴⁰⁰³⁹ is an apocalyptic number.

640039 is a deficient number, since it is larger than the sum of its proper divisors (1).

640039 is an equidigital number, since it uses as much as digits as its factorization.

640039 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 640039 is about 800.0243746287. The cubic root of 640039 is about 86.1791380439.

The spelling of 640039 in words is "six hundred forty thousand, thirty-nine".