638447739 has 8 divisors (see below), whose sum is σ = 853388112. Its totient is φ = 424569600.

The previous prime is 638447723. The next prime is 638447741. The reversal of 638447739 is 937744836.

It is a happy number.

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

It is not a de Polignac number, because 638447739 - 2⁴ = 638447723 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 638447691 and 638447700.

It is not an unprimeable number, because it can be changed into a prime (638447779) 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, 264154 + ... + 266559.

It is an arithmetic number, because the mean of its divisors is an integer number (106673514).

Almost surely, 2^638447739 is an apocalyptic number.

638447739 is a deficient number, since it is larger than the sum of its proper divisors (214940373).

638447739 is a wasteful number, since it uses less digits than its factorization.

638447739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 531117.

The product of its digits is 3048192, while the sum is 51.

The square root of 638447739 is about 25267.5234045602. The cubic root of 638447739 is about 861.0765942805.

The spelling of 638447739 in words is "six hundred thirty-eight million, four hundred forty-seven thousand, seven hundred thirty-nine".