678731 has 2 divisors, whose sum is σ = 678732. Its totient is φ = 678730.

The previous prime is 678721. The next prime is 678739. The reversal of 678731 is 137876.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-678731 is a prime.

It is a super-2 number, since 2×678731² = 921351540722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 678731.

It is not a weakly prime, because it can be changed into another prime (678739) 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, 339365 + 339366.

It is an arithmetic number, because the mean of its divisors is an integer number (339366).

2⁶⁷⁸⁷³¹ is an apocalyptic number.

678731 is a deficient number, since it is larger than the sum of its proper divisors (1).

678731 is an equidigital number, since it uses as much as digits as its factorization.

678731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7056, while the sum is 32.

The square root of 678731 is about 823.8513215381. The cubic root of 678731 is about 87.8818576463.

The spelling of 678731 in words is "six hundred seventy-eight thousand, seven hundred thirty-one".