1688112721 has 8 divisors (see below), whose sum is σ = 1739289384. Its totient is φ = 1637412480.

The previous prime is 1688112709. The next prime is 1688112739. The reversal of 1688112721 is 1272118861.

It can be written as a sum of positive squares in 4 ways, for example, as 200930625 + 1487182096 = 14175^2 + 38564^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1688112721 - 2²⁵ = 1654558289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1688112221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 111906 + ... + 126091.

It is an arithmetic number, because the mean of its divisors is an integer number (217411173).

Almost surely, 2^1688112721 is an apocalyptic number.

It is an amenable number.

1688112721 is a deficient number, since it is larger than the sum of its proper divisors (51176663).

1688112721 is a wasteful number, since it uses less digits than its factorization.

1688112721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238211.

The product of its digits is 10752, while the sum is 37.

The square root of 1688112721 is about 41086.6489385542. The cubic root of 1688112721 is about 1190.6948654598.

The spelling of 1688112721 in words is "one billion, six hundred eighty-eight million, one hundred twelve thousand, seven hundred twenty-one".