640473871 has 2 divisors, whose sum is σ = 640473872. Its totient is φ = 640473870.

The previous prime is 640473791. The next prime is 640473877. The reversal of 640473871 is 178374046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640473871 - 2²¹ = 638376719 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640473877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320236935 + 320236936.

It is an arithmetic number, because the mean of its divisors is an integer number (320236936).

Almost surely, 2^640473871 is an apocalyptic number.

640473871 is a deficient number, since it is larger than the sum of its proper divisors (1).

640473871 is an equidigital number, since it uses as much as digits as its factorization.

640473871 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112896, while the sum is 40.

The square root of 640473871 is about 25307.5852463249. The cubic root of 640473871 is about 861.9865160654.

The spelling of 640473871 in words is "six hundred forty million, four hundred seventy-three thousand, eight hundred seventy-one".