640837073646 has 384 divisors, whose sum is σ = 1887848202240. Its totient is φ = 152047238400.

The previous prime is 640837073641. The next prime is 640837073647. The reversal of 640837073646 is 646370738046.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 640837073592 and 640837073601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640837073641) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 250619400 + ... + 250621956.

It is an arithmetic number, because the mean of its divisors is an integer number (4916271360).

Almost surely, 2^640837073646 is an apocalyptic number.

640837073646 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 640837073646, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (943924101120).

640837073646 is an abundant number, since it is smaller than the sum of its proper divisors (1247011128594).

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

640837073646 is a wasteful number, since it uses less digits than its factorization.

640837073646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2940 (or 2937 counting only the distinct ones).

The product of its (nonzero) digits is 12192768, while the sum is 54.

The spelling of 640837073646 in words is "six hundred forty billion, eight hundred thirty-seven million, seventy-three thousand, six hundred forty-six".