840139 has 2 divisors, whose sum is σ = 840140. Its totient is φ = 840138.

The previous prime is 840137. The next prime is 840149. The reversal of 840139 is 931048.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 840139 - 2¹ = 840137 is a prime.

Together with 840137, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (840137) 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, 420069 + 420070.

It is an arithmetic number, because the mean of its divisors is an integer number (420070).

2⁸⁴⁰¹³⁹ is an apocalyptic number.

840139 is a deficient number, since it is larger than the sum of its proper divisors (1).

840139 is an equidigital number, since it uses as much as digits as its factorization.

840139 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 840139 is about 916.5909665712. The cubic root of 840139 is about 94.3590837595.

Subtracting 840139 from its reverse (931048), we obtain a palindrome (90909).

It can be divided in two parts, 840 and 139, that added together give a palindrome (979).

The spelling of 840139 in words is "eight hundred forty thousand, one hundred thirty-nine".