1688399 has 4 divisors (see below), whose sum is σ = 1693536. Its totient is φ = 1683264.

The previous prime is 1688387. The next prime is 1688411. The reversal of 1688399 is 9938861.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (1688387) and next prime (1688411).

It is a cyclic number.

It is not a de Polignac number, because 1688399 - 2⁸ = 1688143 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 (1688329) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2039 + ... + 2744.

It is an arithmetic number, because the mean of its divisors is an integer number (423384).

2^1688399 is an apocalyptic number.

1688399 is a deficient number, since it is larger than the sum of its proper divisors (5137).

1688399 is an equidigital number, since it uses as much as digits as its factorization.

1688399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5136.

The product of its digits is 93312, while the sum is 44.

The square root of 1688399 is about 1299.3840848648. The cubic root of 1688399 is about 119.0762169747.

The spelling of 1688399 in words is "one million, six hundred eighty-eight thousand, three hundred ninety-nine".