640348905 has 48 divisors (see below), whose sum is σ = 1219610304. Its totient is φ = 285909120.

The previous prime is 640348897. The next prime is 640348921. The reversal of 640348905 is 509843046.

It is not a de Polignac number, because 640348905 - 2³ = 640348897 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 21475 + ... + 41735.

It is an arithmetic number, because the mean of its divisors is an integer number (25408548).

Almost surely, 2^640348905 is an apocalyptic number.

It is an amenable number.

640348905 is a deficient number, since it is larger than the sum of its proper divisors (579261399).

640348905 is a wasteful number, since it uses less digits than its factorization.

640348905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20326 (or 20319 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 39.

The square root of 640348905 is about 25305.1161823059. The cubic root of 640348905 is about 861.9304502790.

The spelling of 640348905 in words is "six hundred forty million, three hundred forty-eight thousand, nine hundred five".