640591871 has 8 divisors (see below), whose sum is σ = 645311184. Its totient is φ = 635880960.

The previous prime is 640591813. The next prime is 640591879. The reversal of 640591871 is 178195046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640591871 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640591879) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 302111 + ... + 304223.

It is an arithmetic number, because the mean of its divisors is an integer number (80663898).

Almost surely, 2^640591871 is an apocalyptic number.

640591871 is a deficient number, since it is larger than the sum of its proper divisors (4719313).

640591871 is a wasteful number, since it uses less digits than its factorization.

640591871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4201.

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 640591871 is about 25309.9164558084. The cubic root of 640591871 is about 862.0394498735.

The spelling of 640591871 in words is "six hundred forty million, five hundred ninety-one thousand, eight hundred seventy-one".