638691027840 has 192 divisors, whose sum is σ = 2214636138000. Its totient is φ = 169610526720.

The previous prime is 638691027839. The next prime is 638691027869. The reversal of 638691027840 is 48720196836.

It is a tau number, because it is divible by the number of its divisors (192).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1158111 + ... + 1618209.

Almost surely, 2^638691027840 is an apocalyptic number.

638691027840 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 638691027840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1107318069000).

638691027840 is an abundant number, since it is smaller than the sum of its proper divisors (1575945110160).

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

638691027840 is a wasteful number, since it uses less digits than its factorization.

638691027840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 460365 (or 460350 counting only the distinct ones).

The product of its (nonzero) digits is 3483648, while the sum is 54.

The spelling of 638691027840 in words is "six hundred thirty-eight billion, six hundred ninety-one million, twenty-seven thousand, eight hundred forty".