639658487492640 has 768 divisors, whose sum is σ = 2795460746158080. Its totient is φ = 132714920448000.

The previous prime is 639658487492627. The next prime is 639658487492641. The reversal of 639658487492640 is 46294784856936.

639658487492640 is a `hidden beast` number, since 6 + 3 + 9 + 6 + 5 + 8 + 4 + 87 + 492 + 6 + 40 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 639658487492640.

It is not an unprimeable number, because it can be changed into a prime (639658487492641) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 218420445 + ... + 221329635.

It is an arithmetic number, because the mean of its divisors is an integer number (3639922846560).

Almost surely, 2^{639658487492640} is an apocalyptic number.

639658487492640 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 639658487492640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1397730373079040).

639658487492640 is an abundant number, since it is smaller than the sum of its proper divisors (2155802258665440).

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

639658487492640 is a wasteful number, since it uses less digits than its factorization.

639658487492640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2909894 (or 2909880 counting only the distinct ones).

The product of its (nonzero) digits is 15049359360, while the sum is 81.

The spelling of 639658487492640 in words is "six hundred thirty-nine trillion, six hundred fifty-eight billion, four hundred eighty-seven million, four hundred ninety-two thousand, six hundred forty".