638681278358 has 4 divisors (see below), whose sum is σ = 958021917540. Its totient is φ = 319340639178.

The previous prime is 638681278309. The next prime is 638681278369. The reversal of 638681278358 is 853872186836.

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

It is a junction number, because it is equal to n+sod(n) for n = 638681278294 and 638681278303.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159670319588 + ... + 159670319591.

It is an arithmetic number, because the mean of its divisors is an integer number (239505479385).

Almost surely, 2^638681278358 is an apocalyptic number.

638681278358 is a deficient number, since it is larger than the sum of its proper divisors (319340639182).

638681278358 is a wasteful number, since it uses less digits than its factorization.

638681278358 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319340639181.

The product of its digits is 92897280, while the sum is 65.

The spelling of 638681278358 in words is "six hundred thirty-eight billion, six hundred eighty-one million, two hundred seventy-eight thousand, three hundred fifty-eight".