640523520 has 648 divisors, whose sum is σ = 2800901376. Its totient is φ = 132268032.

The previous prime is 640523509. The next prime is 640523531. The reversal of 640523520 is 25325046.

640523520 is a `hidden beast` number, since 6 + 405 + 235 + 20 = 666.

It is an interprime number because it is at equal distance from previous prime (640523509) and next prime (640523531).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 13628137 + ... + 13628183.

Almost surely, 2^640523520 is an apocalyptic number.

640523520 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640523520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1400450688).

640523520 is an abundant number, since it is smaller than the sum of its proper divisors (2160377856).

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

640523520 is a wasteful number, since it uses less digits than its factorization.

640523520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107 (or 77 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 27.

The square root of 640523520 is about 25308.5661387602. The cubic root of 640523520 is about 862.0087889816.

Adding to 640523520 its reverse (25325046), we get a palindrome (665848566).

The spelling of 640523520 in words is "six hundred forty million, five hundred twenty-three thousand, five hundred twenty".