640643605401 has 8 divisors (see below), whose sum is σ = 856518972544. Its totient is φ = 425931987600.

The previous prime is 640643605361. The next prime is 640643605429. The reversal of 640643605401 is 104506346046.

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

It is a de Polignac number, because none of the positive numbers 2^k-640643605401 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 640643605401.

It is not an unprimeable number, because it can be changed into a prime (640643605501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 290936050 + ... + 290938251.

It is an arithmetic number, because the mean of its divisors is an integer number (107064871568).

Almost surely, 2^640643605401 is an apocalyptic number.

It is an amenable number.

640643605401 is a deficient number, since it is larger than the sum of its proper divisors (215875367143).

640643605401 is a wasteful number, since it uses less digits than its factorization.

640643605401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 581874671.

The product of its (nonzero) digits is 207360, while the sum is 39.

The spelling of 640643605401 in words is "six hundred forty billion, six hundred forty-three million, six hundred five thousand, four hundred one".