638351606381 has 8 divisors (see below), whose sum is σ = 680437956600. Its totient is φ = 596769284608.

The previous prime is 638351606377. The next prime is 638351606407. The reversal of 638351606381 is 183606153836.

It can be written as a sum of positive squares in 4 ways, for example, as 93657421225 + 544694185156 = 306035^2 + 738034^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 638351606381 - 2² = 638351606377 is a prime.

It is a super-2 number, since 2×638351606381² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638351606281) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 126004496 + ... + 126009561.

It is an arithmetic number, because the mean of its divisors is an integer number (85054744575).

Almost surely, 2^638351606381 is an apocalyptic number.

It is an amenable number.

638351606381 is a deficient number, since it is larger than the sum of its proper divisors (42086350219).

638351606381 is a wasteful number, since it uses less digits than its factorization.

638351606381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252014223.

The product of its (nonzero) digits is 1866240, while the sum is 50.

The spelling of 638351606381 in words is "six hundred thirty-eight billion, three hundred fifty-one million, six hundred six thousand, three hundred eighty-one".