640815319890 has 48 divisors (see below), whose sum is σ = 1711150106328. Its totient is φ = 166265595648.

The previous prime is 640815319847. The next prime is 640815319901. The reversal of 640815319890 is 98913518046.

640815319890 is a `hidden beast` number, since 6 + 408 + 153 + 1 + 9 + 89 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 575402653809 + 65412666081 = 758553^2 + 255759^2 .

It is a super-2 number, since 2×640815319890² (a number of 24 digits) contains 22 as substring.

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, 96215187 + ... + 96221846.

Almost surely, 2^640815319890 is an apocalyptic number.

640815319890 is an abundant number, since it is smaller than the sum of its proper divisors (1070334786438).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640815319890 is a wasteful number, since it uses less digits than its factorization.

640815319890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192437083 (or 192437080 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 54.

The spelling of 640815319890 in words is "six hundred forty billion, eight hundred fifteen million, three hundred nineteen thousand, eight hundred ninety".