781139 has 2 divisors, whose sum is σ = 781140. Its totient is φ = 781138.

The previous prime is 781129. The next prime is 781163. The reversal of 781139 is 931187.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-781139 is a prime.

It is a super-2 number, since 2×781139² = 1220356274642, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (781129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390569 + 390570.

It is an arithmetic number, because the mean of its divisors is an integer number (390570).

2⁷⁸¹¹³⁹ is an apocalyptic number.

781139 is a deficient number, since it is larger than the sum of its proper divisors (1).

781139 is an equidigital number, since it uses as much as digits as its factorization.

781139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 29.

The square root of 781139 is about 883.8206831705. The cubic root of 781139 is about 92.0964253661.

The spelling of 781139 in words is "seven hundred eighty-one thousand, one hundred thirty-nine".