628218281 has 8 divisors (see below), whose sum is σ = 632198664. Its totient is φ = 624245760.

The previous prime is 628218233. The next prime is 628218313. The reversal of 628218281 is 182812826.

It can be written as a sum of positive squares in 4 ways, for example, as 2418025 + 625800256 = 1555^2 + 25016^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 628218281 - 2¹⁰ = 628217257 is a prime.

It is a super-2 number, since 2×628218281² = 789316417165189922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (628218181) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 265355 + ... + 267711.

It is an arithmetic number, because the mean of its divisors is an integer number (79024833).

Almost surely, 2^628218281 is an apocalyptic number.

It is an amenable number.

628218281 is a deficient number, since it is larger than the sum of its proper divisors (3980383).

628218281 is a wasteful number, since it uses less digits than its factorization.

628218281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3931.

The product of its digits is 24576, while the sum is 38.

The square root of 628218281 is about 25064.2829739851. The cubic root of 628218281 is about 856.4529771448.

The spelling of 628218281 in words is "six hundred twenty-eight million, two hundred eighteen thousand, two hundred eighty-one".