640531650 has 72 divisors (see below), whose sum is σ = 1746106992. Its totient is φ = 155276000.

The previous prime is 640531649. The next prime is 640531663. The reversal of 640531650 is 56135046.

640531650 is digitally balanced in base 2 and base 6, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 505 + ... + 35795.

It is an arithmetic number, because the mean of its divisors is an integer number (24251486).

Almost surely, 2^640531650 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640531650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (873053496).

640531650 is an abundant number, since it is smaller than the sum of its proper divisors (1105575342).

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

640531650 is a wasteful number, since it uses less digits than its factorization.

640531650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35328 (or 35312 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 30.

The square root of 640531650 is about 25308.7267558050. The cubic root of 640531650 is about 862.0124360514.

Adding to 640531650 its reverse (56135046), we get a palindrome (696666696).

It can be divided in two parts, 64053 and 1650, that added together give a triangular number (65703 = T₃₆₂).

The spelling of 640531650 in words is "six hundred forty million, five hundred thirty-one thousand, six hundred fifty".