687656399 has 4 divisors (see below), whose sum is σ = 687713664. Its totient is φ = 687599136.

The previous prime is 687656383. The next prime is 687656407. The reversal of 687656399 is 993656786.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 687656399 - 2⁴ = 687656383 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 (687656899) 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 3 ways as a sum of consecutive naturals, for example, 2927 + ... + 37200.

It is an arithmetic number, because the mean of its divisors is an integer number (171928416).

Almost surely, 2^687656399 is an apocalyptic number.

687656399 is a deficient number, since it is larger than the sum of its proper divisors (57265).

687656399 is a wasteful number, since it uses less digits than its factorization.

687656399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57264.

The product of its digits is 14696640, while the sum is 59.

The square root of 687656399 is about 26223.2034465662. The cubic root of 687656399 is about 882.6540051752.

The spelling of 687656399 in words is "six hundred eighty-seven million, six hundred fifty-six thousand, three hundred ninety-nine".