640777 has 2 divisors, whose sum is σ = 640778. Its totient is φ = 640776.

The previous prime is 640771. The next prime is 640793. The reversal of 640777 is 777046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 495616 + 145161 = 704^2 + 381^2 .

It is a cyclic number.

It is not a de Polignac number, because 640777 - 2⁷ = 640649 is a prime.

It is not a weakly prime, because it can be changed into another prime (640771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320388 + 320389.

It is an arithmetic number, because the mean of its divisors is an integer number (320389).

2⁶⁴⁰⁷⁷⁷ is an apocalyptic number.

It is an amenable number.

640777 is a deficient number, since it is larger than the sum of its proper divisors (1).

640777 is an equidigital number, since it uses as much as digits as its factorization.

640777 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8232, while the sum is 31.

The square root of 640777 is about 800.4854776946. The cubic root of 640777 is about 86.2122484089.

The spelling of 640777 in words is "six hundred forty thousand, seven hundred seventy-seven".