687551 has 2 divisors, whose sum is σ = 687552. Its totient is φ = 687550.

The previous prime is 687541. The next prime is 687559. The reversal of 687551 is 155786.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-687551 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343775 + 343776.

It is an arithmetic number, because the mean of its divisors is an integer number (343776).

2⁶⁸⁷⁵⁵¹ is an apocalyptic number.

687551 is a deficient number, since it is larger than the sum of its proper divisors (1).

687551 is an equidigital number, since it uses as much as digits as its factorization.

687551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8400, while the sum is 32.

The square root of 687551 is about 829.1869511757. The cubic root of 687551 is about 88.2608907263.

The spelling of 687551 in words is "six hundred eighty-seven thousand, five hundred fifty-one".