640771 has 2 divisors, whose sum is σ = 640772. Its totient is φ = 640770.

The previous prime is 640741. The next prime is 640777. The reversal of 640771 is 177046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640771 - 2⁹ = 640259 is a prime.

It is not a weakly prime, because it can be changed into another prime (640777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320385 + 320386.

It is an arithmetic number, because the mean of its divisors is an integer number (320386).

2⁶⁴⁰⁷⁷¹ is an apocalyptic number.

640771 is a deficient number, since it is larger than the sum of its proper divisors (1).

640771 is an equidigital number, since it uses as much as digits as its factorization.

640771 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 640771 is about 800.4817299602. The cubic root of 640771 is about 86.2119793215.

The spelling of 640771 in words is "six hundred forty thousand, seven hundred seventy-one".