687849620689 has 27 divisors (see below), whose sum is σ = 879587139753. Its totient is φ = 535936955400.

The previous prime is 687849620677. The next prime is 687849620707. The reversal of 687849620689 is 986026948786.

The square root of 687849620689 is 829367.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 687849620689 - 2³⁹ = 138093806801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (687849620189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 63855874 + ... + 63866644.

Almost surely, 2^687849620689 is an apocalyptic number.

687849620689 is the 829367-th square number.

687849620689 is the 414684-th centered octagonal number.

It is an amenable number.

687849620689 is a deficient number, since it is larger than the sum of its proper divisors (191737519064).

687849620689 is an frugal number, since it uses more digits than its factorization.

687849620689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21578 (or 10789 counting only the distinct ones).

The product of its (nonzero) digits is 501645312, while the sum is 73.

The spelling of 687849620689 in words is "six hundred eighty-seven billion, eight hundred forty-nine million, six hundred twenty thousand, six hundred eighty-nine".