640155344820 has 24 divisors (see below), whose sum is σ = 1792434965664. Its totient is φ = 170708091936.

The previous prime is 640155344819. The next prime is 640155344821. The reversal of 640155344820 is 28443551046.

It is an interprime number because it is at equal distance from previous prime (640155344819) and next prime (640155344821).

It is a super-2 number, since 2×640155344820² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640155344821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5334627814 + ... + 5334627933.

It is an arithmetic number, because the mean of its divisors is an integer number (74684790236).

Almost surely, 2^640155344820 is an apocalyptic number.

640155344820 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

640155344820 is an abundant number, since it is smaller than the sum of its proper divisors (1152279620844).

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

640155344820 is a wasteful number, since it uses less digits than its factorization.

640155344820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10669255759 (or 10669255757 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 42.

Adding to 640155344820 its reverse (28443551046), we get a palindrome (668598895866).

The spelling of 640155344820 in words is "six hundred forty billion, one hundred fifty-five million, three hundred forty-four thousand, eight hundred twenty".