640907616 has 96 divisors (see below), whose sum is σ = 1787184000. Its totient is φ = 200411136.

The previous prime is 640907591. The next prime is 640907621. The reversal of 640907616 is 616709046.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 813975 + ... + 814761.

It is an arithmetic number, because the mean of its divisors is an integer number (18616500).

Almost surely, 2^640907616 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 640907616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (893592000).

640907616 is an abundant number, since it is smaller than the sum of its proper divisors (1146276384).

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

640907616 is a wasteful number, since it uses less digits than its factorization.

640907616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1316 (or 1308 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 39.

The square root of 640907616 is about 25316.1532622948. The cubic root of 640907616 is about 862.1810584655.

The spelling of 640907616 in words is "six hundred forty million, nine hundred seven thousand, six hundred sixteen".