628981 has 12 divisors (see below), whose sum is σ = 696780. Its totient is φ = 566720.

The previous prime is 628973. The next prime is 628993. The reversal of 628981 is 189826.

It can be written as a sum of positive squares in 2 ways, for example, as 152881 + 476100 = 391^2 + 690^2 .

It is not a de Polignac number, because 628981 - 2³ = 628973 is a prime.

It is a super-2 number, since 2×628981² = 791234196722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (628921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15321 + ... + 15361.

It is an arithmetic number, because the mean of its divisors is an integer number (58065).

2⁶²⁸⁹⁸¹ is an apocalyptic number.

It is an amenable number.

628981 is a deficient number, since it is larger than the sum of its proper divisors (67799).

628981 is a wasteful number, since it uses less digits than its factorization.

628981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116 (or 93 counting only the distinct ones).

The product of its digits is 6912, while the sum is 34.

The square root of 628981 is about 793.0832238801. The cubic root of 628981 is about 85.6799443117.

The spelling of 628981 in words is "six hundred twenty-eight thousand, nine hundred eighty-one".