640436620344 has 32 divisors (see below), whose sum is σ = 1602142917120. Its totient is φ = 213338691296.

The previous prime is 640436620277. The next prime is 640436620349. The reversal of 640436620344 is 443026634046.

It is a junction number, because it is equal to n+sod(n) for n = 640436620296 and 640436620305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640436620349) 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, 8724072 + ... + 8797175.

It is an arithmetic number, because the mean of its divisors is an integer number (50066966160).

Almost surely, 2^640436620344 is an apocalyptic number.

It is an amenable number.

640436620344 is an abundant number, since it is smaller than the sum of its proper divisors (961706296776).

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

640436620344 is a wasteful number, since it uses less digits than its factorization.

640436620344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17522779 (or 17522775 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 42.

The spelling of 640436620344 in words is "six hundred forty billion, four hundred thirty-six million, six hundred twenty thousand, three hundred forty-four".