689921 has 2 divisors, whose sum is σ = 689922. Its totient is φ = 689920.

The previous prime is 689917. The next prime is 689929. The reversal of 689921 is 129986.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 541696 + 148225 = 736^2 + 385^2 .

It is a cyclic number.

It is not a de Polignac number, because 689921 - 2² = 689917 is a prime.

It is not a weakly prime, because it can be changed into another prime (689929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344960 + 344961.

It is an arithmetic number, because the mean of its divisors is an integer number (344961).

2⁶⁸⁹⁹²¹ is an apocalyptic number.

It is an amenable number.

689921 is a deficient number, since it is larger than the sum of its proper divisors (1).

689921 is an equidigital number, since it uses as much as digits as its factorization.

689921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 35.

The square root of 689921 is about 830.6148325187. The cubic root of 689921 is about 88.3621866899.

The spelling of 689921 in words is "six hundred eighty-nine thousand, nine hundred twenty-one".