640140671 has 2 divisors, whose sum is σ = 640140672. Its totient is φ = 640140670.

The previous prime is 640140637. The next prime is 640140673. The reversal of 640140671 is 176041046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640140671 - 2¹⁸ = 639878527 is a prime.

Together with 640140673, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640140673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320070335 + 320070336.

It is an arithmetic number, because the mean of its divisors is an integer number (320070336).

Almost surely, 2^640140671 is an apocalyptic number.

640140671 is a deficient number, since it is larger than the sum of its proper divisors (1).

640140671 is an equidigital number, since it uses as much as digits as its factorization.

640140671 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 640140671 is about 25301.0013833445. The cubic root of 640140671 is about 861.8370102379.

The spelling of 640140671 in words is "six hundred forty million, one hundred forty thousand, six hundred seventy-one".