639187121664 has 1440 divisors, whose sum is σ = 2481650851680. Its totient is φ = 156513337344.

The previous prime is 639187121659. The next prime is 639187121689. The reversal of 639187121664 is 466121781936.

639187121664 is a `hidden beast` number, since 6 + 391 + 87 + 12 + 166 + 4 = 666.

It is a super-2 number, since 2×639187121664² (a number of 24 digits) contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 639187121664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 4071255474 + ... + 4071255630.

It is an arithmetic number, because the mean of its divisors is an integer number (1723368647).

Almost surely, 2^639187121664 is an apocalyptic number.

639187121664 is a gapful number since it is divisible by the number (64) 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 639187121664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1240825425840).

639187121664 is an abundant number, since it is smaller than the sum of its proper divisors (1842463730016).

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

639187121664 is a wasteful number, since it uses less digits than its factorization.

639187121664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300 (or 274 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 54.

The spelling of 639187121664 in words is "six hundred thirty-nine billion, one hundred eighty-seven million, one hundred twenty-one thousand, six hundred sixty-four".