639640512 has 252 divisors, whose sum is σ = 2161449576. Its totient is φ = 180311040.

The previous prime is 639640499. The next prime is 639640513. The reversal of 639640512 is 215046936.

It is a happy number.

639640512 is a `hidden beast` number, since 6 + 3 + 9 + 640 + 5 + 1 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (252).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639640513) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3697258 + ... + 3697430.

Almost surely, 2^639640512 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 639640512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1080724788).

639640512 is an abundant number, since it is smaller than the sum of its proper divisors (1521809064).

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

639640512 is a wasteful number, since it uses less digits than its factorization.

639640512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336 (or 316 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The square root of 639640512 is about 25291.1152778995. The cubic root of 639640512 is about 861.6124929973.

The spelling of 639640512 in words is "six hundred thirty-nine million, six hundred forty thousand, five hundred twelve".