1628221 has 16 divisors (see below), whose sum is σ = 1958400. Its totient is φ = 1352400.

The previous prime is 1628203. The next prime is 1628227. The reversal of 1628221 is 1228261.

It is not a de Polignac number, because 1628221 - 2⁷ = 1628093 is a prime.

It is a super-2 number, since 2×1628221² = 5302207249682, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a junction number, because it is equal to n+sod(n) for n = 1628192 and 1628201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1628227) 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 15 ways as a sum of consecutive naturals, for example, 16071 + ... + 16171.

It is an arithmetic number, because the mean of its divisors is an integer number (122400).

2^1628221 is an apocalyptic number.

It is an amenable number.

1628221 is a deficient number, since it is larger than the sum of its proper divisors (330179).

1628221 is an equidigital number, since it uses as much as digits as its factorization.

1628221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169 (or 155 counting only the distinct ones).

The product of its digits is 384, while the sum is 22.

The square root of 1628221 is about 1276.0176331070. The cubic root of 1628221 is about 117.6443615705.

It can be divided in two parts, 1628 and 221, that added together give a square (1849 = 43²).

The spelling of 1628221 in words is "one million, six hundred twenty-eight thousand, two hundred twenty-one".