1678921 has 2 divisors, whose sum is σ = 1678922. Its totient is φ = 1678920.

The previous prime is 1678891. The next prime is 1678951. The reversal of 1678921 is 1298761.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (1678891) and next prime (1678951).

It can be written as a sum of positive squares in only one way, i.e., 1597696 + 81225 = 1264^2 + 285^2 .

It is a cyclic number.

It is not a de Polignac number, because 1678921 - 2⁵ = 1678889 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is not a weakly prime, because it can be changed into another prime (1678951) 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 as a sum of consecutive naturals, namely, 839460 + 839461.

It is an arithmetic number, because the mean of its divisors is an integer number (839461).

2^1678921 is an apocalyptic number.

It is an amenable number.

1678921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1678921 is an equidigital number, since it uses as much as digits as its factorization.

1678921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 34.

The square root of 1678921 is about 1295.7318395409. The cubic root of 1678921 is about 118.8529832405.

The spelling of 1678921 in words is "one million, six hundred seventy-eight thousand, nine hundred twenty-one".