628228781 has 2 divisors, whose sum is σ = 628228782. Its totient is φ = 628228780.

The previous prime is 628228763. The next prime is 628228789. The reversal of 628228781 is 187822826.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 521437225 + 106791556 = 22835^2 + 10334^2 .

It is a cyclic number.

It is not a de Polignac number, because 628228781 - 2⁶ = 628228717 is a prime.

It is a super-2 number, since 2×628228781² = 789342802553491922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (628228789) 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, 314114390 + 314114391.

It is an arithmetic number, because the mean of its divisors is an integer number (314114391).

Almost surely, 2^628228781 is an apocalyptic number.

It is an amenable number.

628228781 is a deficient number, since it is larger than the sum of its proper divisors (1).

628228781 is an equidigital number, since it uses as much as digits as its factorization.

628228781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 172032, while the sum is 44.

The square root of 628228781 is about 25064.4924345178. The cubic root of 628228781 is about 856.4577486849.

The spelling of 628228781 in words is "six hundred twenty-eight million, two hundred twenty-eight thousand, seven hundred eighty-one".