628718509 has 4 divisors (see below), whose sum is σ = 628806204. Its totient is φ = 628630816.

The previous prime is 628718507. The next prime is 628718513. The reversal of 628718509 is 905817826.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 905817826 = 2 ⋅452908913.

It can be written as a sum of positive squares in 2 ways, for example, as 59752900 + 568965609 = 7730^2 + 23853^2 .

It is a cyclic number.

It is not a de Polignac number, because 628718509 - 2¹ = 628718507 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (628718507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32032 + ... + 47785.

It is an arithmetic number, because the mean of its divisors is an integer number (157201551).

Almost surely, 2^628718509 is an apocalyptic number.

It is an amenable number.

628718509 is a deficient number, since it is larger than the sum of its proper divisors (87695).

628718509 is an equidigital number, since it uses as much as digits as its factorization.

628718509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87694.

The product of its (nonzero) digits is 241920, while the sum is 46.

The square root of 628718509 is about 25074.2598893766. The cubic root of 628718509 is about 856.6802379079.

The spelling of 628718509 in words is "six hundred twenty-eight million, seven hundred eighteen thousand, five hundred nine".