640550188738908 has 174 divisors, whose sum is σ = 1921650566216696. Its totient is φ = 183014339639688.

The previous prime is 640550188738891. The next prime is 640550188738921. The reversal of 640550188738908 is 809837881055046.

640550188738908 is a `hidden beast` number, since 6 + 4 + 0 + 5 + 501 + 8 + 87 + 38 + 9 + 0 + 8 = 666.

It is an ABA number since it can be written as A⋅B^A, here for A=28, B=3.

It is a super-2 number, since 2×640550188738908² (a number of 30 digits) contains 22 as substring.

It is a nialpdrome in base 9.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 57 ways as a sum of consecutive naturals, for example, 91507169819841 + ... + 91507169819847.

Almost surely, 2^{640550188738908} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640550188738908, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (960825283108348).

640550188738908 is an abundant number, since it is smaller than the sum of its proper divisors (1281100377477788).

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

640550188738908 is an frugal number, since it uses more digits than its factorization.

640550188738908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95 (or 12 counting only the distinct ones).

The product of its (nonzero) digits is 464486400, while the sum is 72.

The spelling of 640550188738908 in words is "six hundred forty trillion, five hundred fifty billion, one hundred eighty-eight million, seven hundred thirty-eight thousand, nine hundred eight".