640701671 has 2 divisors, whose sum is σ = 640701672. Its totient is φ = 640701670.

The previous prime is 640701653. The next prime is 640701703. The reversal of 640701671 is 176107046.

It is a happy number.

It is an a-pointer prime, because the next prime (640701703) can be obtained adding 640701671 to its sum of digits (32).

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640701671 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640701601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320350835 + 320350836.

It is an arithmetic number, because the mean of its divisors is an integer number (320350836).

Almost surely, 2^640701671 is an apocalyptic number.

640701671 is a deficient number, since it is larger than the sum of its proper divisors (1).

640701671 is an equidigital number, since it uses as much as digits as its factorization.

640701671 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 640701671 is about 25312.0854731490. The cubic root of 640701671 is about 862.0886993923.

The spelling of 640701671 in words is "six hundred forty million, seven hundred one thousand, six hundred seventy-one".