1680728789 has 4 divisors (see below), whose sum is σ = 1716489024. Its totient is φ = 1644968556.

The previous prime is 1680728759. The next prime is 1680728813. The reversal of 1680728789 is 9878270861.

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: 9878270861 = 2633 ⋅3751717.

It is a cyclic number.

It is not a de Polignac number, because 1680728789 - 2¹⁶ = 1680663253 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 (1680728759) 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, 17880047 + ... + 17880140.

It is an arithmetic number, because the mean of its divisors is an integer number (429122256).

Almost surely, 2^1680728789 is an apocalyptic number.

It is an amenable number.

1680728789 is a deficient number, since it is larger than the sum of its proper divisors (35760235).

1680728789 is an equidigital number, since it uses as much as digits as its factorization.

1680728789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35760234.

The product of its (nonzero) digits is 2709504, while the sum is 56.

The square root of 1680728789 is about 40996.6924153644. The cubic root of 1680728789 is about 1188.9562651040.

The spelling of 1680728789 in words is "one billion, six hundred eighty million, seven hundred twenty-eight thousand, seven hundred eighty-nine".