638360868565221 has 16 divisors (see below), whose sum is σ = 865529973125568. Its totient is φ = 418389756019200.

The previous prime is 638360868565169. The next prime is 638360868565229. The reversal of 638360868565221 is 122565868063836.

638360868565221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 638360868565221 - 2³⁰ = 638359794823397 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638360868565229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 864358395 + ... + 865096616.

It is an arithmetic number, because the mean of its divisors is an integer number (54095623320348).

Almost surely, 2^{638360868565221} is an apocalyptic number.

638360868565221 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

638360868565221 is a deficient number, since it is larger than the sum of its proper divisors (227169104560347).

638360868565221 is a wasteful number, since it uses less digits than its factorization.

638360868565221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1729457092.

The product of its (nonzero) digits is 597196800, while the sum is 69.

The spelling of 638360868565221 in words is "six hundred thirty-eight trillion, three hundred sixty billion, eight hundred sixty-eight million, five hundred sixty-five thousand, two hundred twenty-one".