640622208 has 64 divisors (see below), whose sum is σ = 1725693120. Its totient is φ = 210524160.

The previous prime is 640622207. The next prime is 640622249. The reversal of 640622208 is 802226046.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (640622207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15516 + ... + 39012.

It is an arithmetic number, because the mean of its divisors is an integer number (26963955).

Almost surely, 2^640622208 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 640622208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (862846560).

640622208 is an abundant number, since it is smaller than the sum of its proper divisors (1085070912).

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

640622208 is a wasteful number, since it uses less digits than its factorization.

640622208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23585 (or 23573 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The square root of 640622208 is about 25310.5157592650. The cubic root of 640622208 is about 862.0530577462.

The spelling of 640622208 in words is "six hundred forty million, six hundred twenty-two thousand, two hundred eight".