640648321378 has 48 divisors (see below), whose sum is σ = 1054575612216. Its totient is φ = 290087032320.

The previous prime is 640648321349. The next prime is 640648321429. The reversal of 640648321378 is 873123846046.

It can be written as a sum of positive squares in 4 ways, for example, as 420924571369 + 219723750009 = 648787^2 + 468747^2 .

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 655729626 + ... + 655730602.

Almost surely, 2^640648321378 is an apocalyptic number.

640648321378 is a deficient number, since it is larger than the sum of its proper divisors (413927290838).

640648321378 is an equidigital number, since it uses as much as digits as its factorization.

640648321378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2339 (or 1696 counting only the distinct ones).

The product of its (nonzero) digits is 4644864, while the sum is 52.

The spelling of 640648321378 in words is "six hundred forty billion, six hundred forty-eight million, three hundred twenty-one thousand, three hundred seventy-eight".