670781 has 2 divisors, whose sum is σ = 670782. Its totient is φ = 670780.

The previous prime is 670777. The next prime is 670811. The reversal of 670781 is 187076.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 502681 + 168100 = 709^2 + 410^2 .

It is a cyclic number.

It is not a de Polignac number, because 670781 - 2² = 670777 is a prime.

It is a super-2 number, since 2×670781² = 899894299922, which contains 22 as substring.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (670711) 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, 335390 + 335391.

It is an arithmetic number, because the mean of its divisors is an integer number (335391).

2⁶⁷⁰⁷⁸¹ is an apocalyptic number.

It is an amenable number.

670781 is a deficient number, since it is larger than the sum of its proper divisors (1).

670781 is an equidigital number, since it uses as much as digits as its factorization.

670781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2352, while the sum is 29.

The square root of 670781 is about 819.0122099212. The cubic root of 670781 is about 87.5373881037.

The spelling of 670781 in words is "six hundred seventy thousand, seven hundred eighty-one".