640548971 has 2 divisors, whose sum is σ = 640548972. Its totient is φ = 640548970.

The previous prime is 640548949. The next prime is 640548989. The reversal of 640548971 is 179845046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640548971 - 2⁶ = 640548907 is a prime.

It is not a weakly prime, because it can be changed into another prime (640548911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320274485 + 320274486.

It is an arithmetic number, because the mean of its divisors is an integer number (320274486).

Almost surely, 2^640548971 is an apocalyptic number.

640548971 is a deficient number, since it is larger than the sum of its proper divisors (1).

640548971 is an equidigital number, since it uses as much as digits as its factorization.

640548971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 241920, while the sum is 44.

The square root of 640548971 is about 25309.0689477112. The cubic root of 640548971 is about 862.0202060462.

The spelling of 640548971 in words is "six hundred forty million, five hundred forty-eight thousand, nine hundred seventy-one".