638560390121 has 4 divisors (see below), whose sum is σ = 640739777412. Its totient is φ = 636381002832.

The previous prime is 638560390073. The next prime is 638560390157. The reversal of 638560390121 is 121093065836.

638560390121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 288734275600 + 349826114521 = 537340^2 + 591461^2 .

It is a cyclic number.

It is not a de Polignac number, because 638560390121 - 2¹⁸ = 638560127977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638560390021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1089693206 + ... + 1089693791.

It is an arithmetic number, because the mean of its divisors is an integer number (160184944353).

Almost surely, 2^638560390121 is an apocalyptic number.

It is an amenable number.

638560390121 is a deficient number, since it is larger than the sum of its proper divisors (2179387291).

638560390121 is a wasteful number, since it uses less digits than its factorization.

638560390121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2179387290.

The product of its (nonzero) digits is 233280, while the sum is 44.

The spelling of 638560390121 in words is "six hundred thirty-eight billion, five hundred sixty million, three hundred ninety thousand, one hundred twenty-one".