1678221 has 6 divisors (see below), whose sum is σ = 2424110. Its totient is φ = 1118808.

The previous prime is 1678219. The next prime is 1678231. The reversal of 1678221 is 1228761.

It can be written as a sum of positive squares in only one way, i.e., 1022121 + 656100 = 1011^2 + 810^2 .

It is not a de Polignac number, because 1678221 - 2¹ = 1678219 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 (1678231) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 93226 + ... + 93243.

2^1678221 is an apocalyptic number.

It is an amenable number.

1678221 is a deficient number, since it is larger than the sum of its proper divisors (745889).

1678221 is a wasteful number, since it uses less digits than its factorization.

1678221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186475 (or 186472 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 1678221 is about 1295.4616937602. The cubic root of 1678221 is about 118.8364629767.

The spelling of 1678221 in words is "one million, six hundred seventy-eight thousand, two hundred twenty-one".