628995809 has 4 divisors (see below), whose sum is σ = 677380116. Its totient is φ = 580611504.

The previous prime is 628995803. The next prime is 628995863. The reversal of 628995809 is 908599826.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 908599826 = 2 ⋅454299913.

It can be written as a sum of positive squares in 2 ways, for example, as 104448400 + 524547409 = 10220^2 + 22903^2 .

It is a cyclic number.

It is not a de Polignac number, because 628995809 - 2⁴ = 628995793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (628995803) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24192134 + ... + 24192159.

It is an arithmetic number, because the mean of its divisors is an integer number (169345029).

Almost surely, 2^628995809 is an apocalyptic number.

It is an amenable number.

628995809 is a deficient number, since it is larger than the sum of its proper divisors (48384307).

628995809 is a wasteful number, since it uses less digits than its factorization.

628995809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48384306.

The product of its (nonzero) digits is 2799360, while the sum is 56.

The square root of 628995809 is about 25079.7888547731. The cubic root of 628995809 is about 856.8061673499.

The spelling of 628995809 in words is "six hundred twenty-eight million, nine hundred ninety-five thousand, eight hundred nine".