640656213605 has 8 divisors (see below), whose sum is σ = 774840901632. Its totient is φ = 508489340688.

The previous prime is 640656213553. The next prime is 640656213629. The reversal of 640656213605 is 506312656046.

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

It is a cyclic number.

It is not a de Polignac number, because 640656213605 - 2⁶ = 640656213541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 504453077 + ... + 504454346.

It is an arithmetic number, because the mean of its divisors is an integer number (96855112704).

Almost surely, 2^640656213605 is an apocalyptic number.

It is an amenable number.

640656213605 is a deficient number, since it is larger than the sum of its proper divisors (134184688027).

640656213605 is a wasteful number, since it uses less digits than its factorization.

640656213605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1008907555.

The product of its (nonzero) digits is 777600, while the sum is 44.

The spelling of 640656213605 in words is "six hundred forty billion, six hundred fifty-six million, two hundred thirteen thousand, six hundred five".