687189985 has 4 divisors (see below), whose sum is σ = 824627988. Its totient is φ = 549751984.

The previous prime is 687189947. The next prime is 687190037. The reversal of 687189985 is 589981786.

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

It can be written as a sum of positive squares in 2 ways, for example, as 171400464 + 515789521 = 13092^2 + 22711^2 .

It is a cyclic number.

It is not a de Polignac number, because 687189985 - 2⁷ = 687189857 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68718994 + ... + 68719003.

It is an arithmetic number, because the mean of its divisors is an integer number (206156997).

Almost surely, 2^687189985 is an apocalyptic number.

It is an amenable number.

687189985 is a deficient number, since it is larger than the sum of its proper divisors (137438003).

687189985 is a wasteful number, since it uses less digits than its factorization.

687189985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137438002.

The product of its digits is 8709120, while the sum is 61.

The square root of 687189985 is about 26214.3087835632. The cubic root of 687189985 is about 882.4544019540.

The spelling of 687189985 in words is "six hundred eighty-seven million, one hundred eighty-nine thousand, nine hundred eighty-five".