640765536 has 96 divisors (see below), whose sum is σ = 1749888000. Its totient is φ = 205079040.

The previous prime is 640765529. The next prime is 640765537. The reversal of 640765536 is 635567046.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640765537) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 412890 + ... + 414438.

It is an arithmetic number, because the mean of its divisors is an integer number (18228000).

Almost surely, 2^640765536 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 640765536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (874944000).

640765536 is an abundant number, since it is smaller than the sum of its proper divisors (1109122464).

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

640765536 is a wasteful number, since it uses less digits than its factorization.

640765536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1732 (or 1724 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 42.

The square root of 640765536 is about 25313.3469932366. The cubic root of 640765536 is about 862.1173427105.

The spelling of 640765536 in words is "six hundred forty million, seven hundred sixty-five thousand, five hundred thirty-six".