638896908391 has 8 divisors (see below), whose sum is σ = 747148544384. Its totient is φ = 534890434680.

The previous prime is 638896908383. The next prime is 638896908409. The reversal of 638896908391 is 193809698836.

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

It is not a de Polignac number, because 638896908391 - 2³ = 638896908383 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 638896908391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638896906391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1061290245 + ... + 1061290846.

It is an arithmetic number, because the mean of its divisors is an integer number (93393568048).

Almost surely, 2^638896908391 is an apocalyptic number.

638896908391 is a deficient number, since it is larger than the sum of its proper divisors (108251635993).

638896908391 is a wasteful number, since it uses less digits than its factorization.

638896908391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2122581141.

The product of its (nonzero) digits is 120932352, while the sum is 70.

The spelling of 638896908391 in words is "six hundred thirty-eight billion, eight hundred ninety-six million, nine hundred eight thousand, three hundred ninety-one".