687687761 has 2 divisors, whose sum is σ = 687687762. Its totient is φ = 687687760.

The previous prime is 687687743. The next prime is 687687769. The reversal of 687687761 is 167786786.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 666930625 + 20757136 = 25825^2 + 4556^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-687687761 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 687687697 and 687687706.

It is not a weakly prime, because it can be changed into another prime (687687769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343843880 + 343843881.

It is an arithmetic number, because the mean of its divisors is an integer number (343843881).

Almost surely, 2^687687761 is an apocalyptic number.

It is an amenable number.

687687761 is a deficient number, since it is larger than the sum of its proper divisors (1).

687687761 is an equidigital number, since it uses as much as digits as its factorization.

687687761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4741632, while the sum is 56.

The square root of 687687761 is about 26223.8014216093. The cubic root of 687687761 is about 882.6674233950.

The spelling of 687687761 in words is "six hundred eighty-seven million, six hundred eighty-seven thousand, seven hundred sixty-one".