688509987 has 8 divisors (see below), whose sum is σ = 1001469120. Its totient is φ = 417278760.

The previous prime is 688509961. The next prime is 688510021. The reversal of 688509987 is 789905886.

It is a happy number.

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

It is not a de Polignac number, because 688509987 - 2¹⁰ = 688508963 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 688509987.

It is not an unprimeable number, because it can be changed into a prime (688509947) 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, 10431937 + ... + 10432002.

It is an arithmetic number, because the mean of its divisors is an integer number (125183640).

Almost surely, 2^688509987 is an apocalyptic number.

688509987 is a deficient number, since it is larger than the sum of its proper divisors (312959133).

688509987 is a wasteful number, since it uses less digits than its factorization.

688509987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20863953.

The product of its (nonzero) digits is 8709120, while the sum is 60.

The square root of 688509987 is about 26239.4738323771. The cubic root of 688509987 is about 883.0190670199.

The spelling of 688509987 in words is "six hundred eighty-eight million, five hundred nine thousand, nine hundred eighty-seven".