1686401 has 4 divisors (see below), whose sum is σ = 1690032. Its totient is φ = 1682772.

The previous prime is 1686389. The next prime is 1686403. The reversal of 1686401 is 1046861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1046861 = 127 ⋅8243.

It is a cyclic number.

It is not a de Polignac number, because 1686401 - 2¹⁴ = 1670017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1686403) 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 3 ways as a sum of consecutive naturals, for example, 995 + ... + 2088.

It is an arithmetic number, because the mean of its divisors is an integer number (422508).

2^1686401 is an apocalyptic number.

It is an amenable number.

1686401 is a deficient number, since it is larger than the sum of its proper divisors (3631).

1686401 is an equidigital number, since it uses as much as digits as its factorization.

1686401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3630.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 1686401 is about 1298.6150314855. The cubic root of 1686401 is about 119.0292280441.

The spelling of 1686401 in words is "one million, six hundred eighty-six thousand, four hundred one".