628628409 has 12 divisors (see below), whose sum is σ = 932560356. Its totient is φ = 407758752.

The previous prime is 628628381. The next prime is 628628423. The reversal of 628628409 is 904826826.

It can be written as a sum of positive squares in 2 ways, for example, as 419102784 + 209525625 = 20472^2 + 14475^2 .

It is not a de Polignac number, because 628628409 - 2¹³ = 628620217 is a prime.

It is not an unprimeable number, because it can be changed into a prime (628628809) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 943554 + ... + 944219.

It is an arithmetic number, because the mean of its divisors is an integer number (77713363).

Almost surely, 2^628628409 is an apocalyptic number.

It is an amenable number.

628628409 is a deficient number, since it is larger than the sum of its proper divisors (303931947).

628628409 is a wasteful number, since it uses less digits than its factorization.

628628409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1887816 (or 1887813 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 45.

The square root of 628628409 is about 25072.4631618036. The cubic root of 628628409 is about 856.6393130871.

The spelling of 628628409 in words is "six hundred twenty-eight million, six hundred twenty-eight thousand, four hundred nine".