687860821 has 16 divisors (see below), whose sum is σ = 720966400. Its totient is φ = 655656768.

The previous prime is 687860791. The next prime is 687860837. The reversal of 687860821 is 128068786.

It is a cyclic number.

It is not a de Polignac number, because 687860821 - 2¹³ = 687852629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687860861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 405451 + ... + 407143.

It is an arithmetic number, because the mean of its divisors is an integer number (45060400).

Almost surely, 2^687860821 is an apocalyptic number.

It is an amenable number.

687860821 is a deficient number, since it is larger than the sum of its proper divisors (33105579).

687860821 is a wasteful number, since it uses less digits than its factorization.

687860821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1948.

The product of its (nonzero) digits is 258048, while the sum is 46.

The square root of 687860821 is about 26227.1008882034. The cubic root of 687860821 is about 882.7414597145.

The spelling of 687860821 in words is "six hundred eighty-seven million, eight hundred sixty thousand, eight hundred twenty-one".