640985598 has 48 divisors (see below), whose sum is σ = 1522840176. Its totient is φ = 193240320.

The previous prime is 640985593. The next prime is 640985641. The reversal of 640985598 is 895589046.

It is a happy number.

640985598 is a `hidden beast` number, since 6 + 40 + 9 + 8 + 5 + 598 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640985593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30790 + ... + 47222.

It is an arithmetic number, because the mean of its divisors is an integer number (31725837).

Almost surely, 2^640985598 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640985598, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (761420088).

640985598 is an abundant number, since it is smaller than the sum of its proper divisors (881854578).

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

640985598 is a wasteful number, since it uses less digits than its factorization.

640985598 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16649 (or 16646 counting only the distinct ones).

The product of its (nonzero) digits is 3110400, while the sum is 54.

The square root of 640985598 is about 25317.6933783471. The cubic root of 640985598 is about 862.2160254794.

It can be divided in two parts, 64098 and 5598, that added together give a palindrome (69696).

The spelling of 640985598 in words is "six hundred forty million, nine hundred eighty-five thousand, five hundred ninety-eight".