1688726321 has 4 divisors (see below), whose sum is σ = 1696165872. Its totient is φ = 1681286772.

The previous prime is 1688726311. The next prime is 1688726329. The reversal of 1688726321 is 1236278861.

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: 1236278861 = 59 ⋅20953879.

It is a cyclic number.

It is not a de Polignac number, because 1688726321 - 2²⁶ = 1621617457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1688726329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3719435 + ... + 3719888.

It is an arithmetic number, because the mean of its divisors is an integer number (424041468).

Almost surely, 2^1688726321 is an apocalyptic number.

It is an amenable number.

1688726321 is a deficient number, since it is larger than the sum of its proper divisors (7439551).

1688726321 is an equidigital number, since it uses as much as digits as its factorization.

1688726321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7439550.

The product of its digits is 193536, while the sum is 44.

The square root of 1688726321 is about 41094.1154059800. The cubic root of 1688726321 is about 1190.8391136996.

The spelling of 1688726321 in words is "one billion, six hundred eighty-eight million, seven hundred twenty-six thousand, three hundred twenty-one".