645879031812 has 144 divisors (see below), whose sum is σ = 1892783692800. Its totient is φ = 181877088960.

The previous prime is 645879031801. The next prime is 645879031841. The reversal of 645879031812 is 218130978546.

645879031812 is a `hidden beast` number, since 6 + 458 + 7 + 9 + 0 + 3 + 181 + 2 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 101247639 + ... + 101254017.

It is an arithmetic number, because the mean of its divisors is an integer number (13144331200).

It is a 2-persistent number, because it is pandigital, and so is 2⋅645879031812 = 1291758063624, but 3⋅645879031812 = 1937637095436 is not.

Almost surely, 2^645879031812 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 645879031812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (946391846400).

645879031812 is an abundant number, since it is smaller than the sum of its proper divisors (1246904660988).

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

645879031812 is a wasteful number, since it uses less digits than its factorization.

645879031812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12126 (or 12121 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The spelling of 645879031812 in words is "six hundred forty-five billion, eight hundred seventy-nine million, thirty-one thousand, eight hundred twelve".