687007661 has 2 divisors, whose sum is σ = 687007662. Its totient is φ = 687007660.

The previous prime is 687007619. The next prime is 687007663. The reversal of 687007661 is 166700786.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 640849225 + 46158436 = 25315^2 + 6794^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-687007661 is a prime.

It is a Sophie Germain prime.

Together with 687007663, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687007663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343503830 + 343503831.

It is an arithmetic number, because the mean of its divisors is an integer number (343503831).

Almost surely, 2^687007661 is an apocalyptic number.

It is an amenable number.

687007661 is a deficient number, since it is larger than the sum of its proper divisors (1).

687007661 is an equidigital number, since it uses as much as digits as its factorization.

687007661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84672, while the sum is 41.

The square root of 687007661 is about 26210.8309864453. The cubic root of 687007661 is about 882.3763513173.

The spelling of 687007661 in words is "six hundred eighty-seven million, seven thousand, six hundred sixty-one".