628781 has 2 divisors, whose sum is σ = 628782. Its totient is φ = 628780.

The previous prime is 628759. The next prime is 628783. The reversal of 628781 is 187826.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 586756 + 42025 = 766^2 + 205^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-628781 is a prime.

It is a super-2 number, since 2×628781² = 790731091922, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 628783, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 628781.

It is not a weakly prime, because it can be changed into another prime (628783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 314390 + 314391.

It is an arithmetic number, because the mean of its divisors is an integer number (314391).

2⁶²⁸⁷⁸¹ is an apocalyptic number.

It is an amenable number.

628781 is a deficient number, since it is larger than the sum of its proper divisors (1).

628781 is an equidigital number, since it uses as much as digits as its factorization.

628781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5376, while the sum is 32.

The square root of 628781 is about 792.9571236832. The cubic root of 628781 is about 85.6708619995.

The spelling of 628781 in words is "six hundred twenty-eight thousand, seven hundred eighty-one".