687881391 has 8 divisors (see below), whose sum is σ = 917449344. Its totient is φ = 458450520.

The previous prime is 687881357. The next prime is 687881419. The reversal of 687881391 is 193188786.

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

It is not a de Polignac number, because 687881391 - 2¹⁷ = 687750319 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687881321) 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 7 ways as a sum of consecutive naturals, for example, 21925 + ... + 43086.

It is an arithmetic number, because the mean of its divisors is an integer number (114681168).

Almost surely, 2^687881391 is an apocalyptic number.

687881391 is a deficient number, since it is larger than the sum of its proper divisors (229567953).

687881391 is a wasteful number, since it uses less digits than its factorization.

687881391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68541.

The product of its digits is 580608, while the sum is 51.

The square root of 687881391 is about 26227.4930368878. The cubic root of 687881391 is about 882.7502588835.

The spelling of 687881391 in words is "six hundred eighty-seven million, eight hundred eighty-one thousand, three hundred ninety-one".