640164229128 has 84 divisors (see below), whose sum is σ = 1799810424765. Its totient is φ = 213367709088.

The previous prime is 640164229127. The next prime is 640164229147. The reversal of 640164229128 is 821922461046.

It is a happy number.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

640164229128 is a `hidden beast` number, since 6 + 401 + 6 + 4 + 229 + 12 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 594043230564 + 46120998564 = 770742^2 + 214758^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=565758.

It is not an unprimeable number, because it can be changed into a prime (640164229121) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 61096626 + ... + 61107102.

Almost surely, 2^640164229128 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 640164229128

640164229128 is an abundant number, since it is smaller than the sum of its proper divisors (1159646195637).

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

640164229128 is an frugal number, since it uses more digits than its factorization.

640164229128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20978 (or 10482 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 45.

The spelling of 640164229128 in words is "six hundred forty billion, one hundred sixty-four million, two hundred twenty-nine thousand, one hundred twenty-eight".