628991 has 8 divisors (see below), whose sum is σ = 691968. Its totient is φ = 567000.

The previous prime is 628973. The next prime is 628993. The reversal of 628991 is 199826.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-628991 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 (628993) 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 in 7 ways as a sum of consecutive naturals, for example, 2186 + ... + 2456.

It is an arithmetic number, because the mean of its divisors is an integer number (86496).

2⁶²⁸⁹⁹¹ is an apocalyptic number.

628991 is a deficient number, since it is larger than the sum of its proper divisors (62977).

628991 is a wasteful number, since it uses less digits than its factorization.

628991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493.

The product of its digits is 7776, while the sum is 35.

The square root of 628991 is about 793.0895283636. The cubic root of 628991 is about 85.6803983768.

The spelling of 628991 in words is "six hundred twenty-eight thousand, nine hundred ninety-one".