628821 has 12 divisors (see below), whose sum is σ = 918060. Its totient is φ = 414720.

The previous prime is 628819. The next prime is 628841. The reversal of 628821 is 128826.

It can be written as a sum of positive squares in 2 ways, for example, as 509796 + 119025 = 714^2 + 345^2 .

It is not a de Polignac number, because 628821 - 2¹ = 628819 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a nialpdrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (628801) 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, 661 + ... + 1301.

It is an arithmetic number, because the mean of its divisors is an integer number (76505).

2⁶²⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

628821 is a deficient number, since it is larger than the sum of its proper divisors (289239).

628821 is a wasteful number, since it uses less digits than its factorization.

628821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 756 (or 753 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 628821 is about 792.9823453268. The cubic root of 628821 is about 85.6726786160.

The spelling of 628821 in words is "six hundred twenty-eight thousand, eight hundred twenty-one".