643697 has 2 divisors, whose sum is σ = 643698. Its totient is φ = 643696.

The previous prime is 643693. The next prime is 643703. The reversal of 643697 is 796346.

643697 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 516961 + 126736 = 719^2 + 356^2 .

It is a cyclic number.

It is not a de Polignac number, because 643697 - 2² = 643693 is a prime.

It is a Chen prime.

It is a d-powerful number, because it can be written as 6 + 4⁸ + 6⁶ + 3¹² + 9 + 7² .

It is not a weakly prime, because it can be changed into another prime (643691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321848 + 321849.

It is an arithmetic number, because the mean of its divisors is an integer number (321849).

2⁶⁴³⁶⁹⁷ is an apocalyptic number.

It is an amenable number.

643697 is a deficient number, since it is larger than the sum of its proper divisors (1).

643697 is an equidigital number, since it uses as much as digits as its factorization.

643697 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 35.

The square root of 643697 is about 802.3072977357. The cubic root of 643697 is about 86.3430054640.

The spelling of 643697 in words is "six hundred forty-three thousand, six hundred ninety-seven".