640139 has 2 divisors, whose sum is σ = 640140. Its totient is φ = 640138.

The previous prime is 640127. The next prime is 640151. The reversal of 640139 is 931046.

It is a balanced prime because it is at equal distance from previous prime (640127) and next prime (640151).

It is a cyclic number.

It is not a de Polignac number, because 640139 - 2¹² = 636043 is a prime.

It is a Chen prime.

It is equal to p₅₂₀₈₈ and since 640139 and 52088 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (640109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320069 + 320070.

It is an arithmetic number, because the mean of its divisors is an integer number (320070).

2⁶⁴⁰¹³⁹ is an apocalyptic number.

640139 is a deficient number, since it is larger than the sum of its proper divisors (1).

640139 is an equidigital number, since it uses as much as digits as its factorization.

640139 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 23.

The square root of 640139 is about 800.0868702835. The cubic root of 640139 is about 86.1836260335.

The spelling of 640139 in words is "six hundred forty thousand, one hundred thirty-nine".