638431739 has 4 divisors (see below), whose sum is σ = 696471000. Its totient is φ = 580392480.

The previous prime is 638431733. The next prime is 638431741. The reversal of 638431739 is 937134836.

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

It is a cyclic number.

It is not a de Polignac number, because 638431739 - 2¹⁶ = 638366203 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 638431739.

It is not an unprimeable number, because it can be changed into a prime (638431733) 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 3 ways as a sum of consecutive naturals, for example, 29019614 + ... + 29019635.

It is an arithmetic number, because the mean of its divisors is an integer number (174117750).

Almost surely, 2^638431739 is an apocalyptic number.

638431739 is a deficient number, since it is larger than the sum of its proper divisors (58039261).

638431739 is a wasteful number, since it uses less digits than its factorization.

638431739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58039260.

The product of its digits is 326592, while the sum is 44.

The square root of 638431739 is about 25267.2067906209. The cubic root of 638431739 is about 861.0694011360.

The spelling of 638431739 in words is "six hundred thirty-eight million, four hundred thirty-one thousand, seven hundred thirty-nine".