640677859 has 2 divisors, whose sum is σ = 640677860. Its totient is φ = 640677858.

The previous prime is 640677847. The next prime is 640677871. The reversal of 640677859 is 958776046.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (640677847) and next prime (640677871).

It is a cyclic number.

It is not a de Polignac number, because 640677859 - 2¹¹ = 640675811 is a prime.

It is not a weakly prime, because it can be changed into another prime (640671859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320338929 + 320338930.

It is an arithmetic number, because the mean of its divisors is an integer number (320338930).

Almost surely, 2^640677859 is an apocalyptic number.

640677859 is a deficient number, since it is larger than the sum of its proper divisors (1).

640677859 is an equidigital number, since it uses as much as digits as its factorization.

640677859 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2540160, while the sum is 52.

The square root of 640677859 is about 25311.6151005818. The cubic root of 640677859 is about 862.0780192732.

The spelling of 640677859 in words is "six hundred forty million, six hundred seventy-seven thousand, eight hundred fifty-nine".