688628987 has 2 divisors, whose sum is σ = 688628988. Its totient is φ = 688628986.

The previous prime is 688628981. The next prime is 688628999. The reversal of 688628987 is 789826886.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 688628987 - 2⁶ = 688628923 is a prime.

It is not a weakly prime, because it can be changed into another prime (688628981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344314493 + 344314494.

It is an arithmetic number, because the mean of its divisors is an integer number (344314494).

Almost surely, 2^688628987 is an apocalyptic number.

688628987 is a deficient number, since it is larger than the sum of its proper divisors (1).

688628987 is an equidigital number, since it uses as much as digits as its factorization.

688628987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18579456, while the sum is 62.

The square root of 688628987 is about 26241.7413103628. The cubic root of 688628987 is about 883.0699368778.

The spelling of 688628987 in words is "six hundred eighty-eight million, six hundred twenty-eight thousand, nine hundred eighty-seven".