687131920 has 20 divisors (see below), whose sum is σ = 1597581900. Its totient is φ = 274852736.

The previous prime is 687131911. The next prime is 687131933. The reversal of 687131920 is 29131786.

It can be written as a sum of positive squares in 2 ways, for example, as 373416976 + 313714944 = 19324^2 + 17712^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 687131920.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 4294495 + ... + 4294654.

It is an arithmetic number, because the mean of its divisors is an integer number (79879095).

Almost surely, 2^687131920 is an apocalyptic number.

It is an amenable number.

687131920 is an abundant number, since it is smaller than the sum of its proper divisors (910449980).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

687131920 is a wasteful number, since it uses less digits than its factorization.

687131920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8589162 (or 8589156 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 687131920 is about 26213.2012543298. The cubic root of 687131920 is about 882.4295465481.

The spelling of 687131920 in words is "six hundred eighty-seven million, one hundred thirty-one thousand, nine hundred twenty".