641909 has 2 divisors, whose sum is σ = 641910. Its totient is φ = 641908.

The previous prime is 641897. The next prime is 641923. The reversal of 641909 is 909146.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 386884 + 255025 = 622^2 + 505^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-641909 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (641929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320954 + 320955.

It is an arithmetic number, because the mean of its divisors is an integer number (320955).

2⁶⁴¹⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

641909 is a deficient number, since it is larger than the sum of its proper divisors (1).

641909 is an equidigital number, since it uses as much as digits as its factorization.

641909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 641909 is about 801.1922366074. The cubic root of 641909 is about 86.2629862124.

The spelling of 641909 in words is "six hundred forty-one thousand, nine hundred nine".