628639709 has 4 divisors (see below), whose sum is σ = 638945340. Its totient is φ = 618334080.

The previous prime is 628639691. The next prime is 628639717. The reversal of 628639709 is 907936826.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 32205625 + 596434084 = 5675^2 + 24422^2 .

It is a cyclic number.

It is not a de Polignac number, because 628639709 - 2¹² = 628635613 is a prime.

It is a super-4 number, since 4×628639709⁴ (a number of 36 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (628639729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5152724 + ... + 5152845.

It is an arithmetic number, because the mean of its divisors is an integer number (159736335).

Almost surely, 2^628639709 is an apocalyptic number.

It is an amenable number.

628639709 is a deficient number, since it is larger than the sum of its proper divisors (10305631).

628639709 is a wasteful number, since it uses less digits than its factorization.

628639709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10305630.

The product of its (nonzero) digits is 979776, while the sum is 50.

The square root of 628639709 is about 25072.6885076172. The cubic root of 628639709 is about 856.6444459372.

The spelling of 628639709 in words is "six hundred twenty-eight million, six hundred thirty-nine thousand, seven hundred nine".