8720689 has 2 divisors, whose sum is σ = 8720690. Its totient is φ = 8720688.

The previous prime is 8720687. The next prime is 8720693. The reversal of 8720689 is 9860278.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6718464 + 2002225 = 2592^2 + 1415^2 .

It is a cyclic number.

It is not a de Polignac number, because 8720689 - 2¹ = 8720687 is a prime.

Together with 8720687, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (8720681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4360344 + 4360345.

It is an arithmetic number, because the mean of its divisors is an integer number (4360345).

Almost surely, 2^8720689 is an apocalyptic number.

It is an amenable number.

8720689 is a deficient number, since it is larger than the sum of its proper divisors (1).

8720689 is an equidigital number, since it uses as much as digits as its factorization.

8720689 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48384, while the sum is 40.

The square root of 8720689 is about 2953.0812721630. The cubic root of 8720689 is about 205.8339142660.

It can be divided in two parts, 8720 and 689, that added together give a square (9409 = 97²).

The spelling of 8720689 in words is "eight million, seven hundred twenty thousand, six hundred eighty-nine".