638747399 has 4 divisors (see below), whose sum is σ = 639783264. Its totient is φ = 637711536.

The previous prime is 638747383. The next prime is 638747411. The reversal of 638747399 is 993747836.

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 638747399 - 2⁴ = 638747383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638747699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 517007 + ... + 518240.

It is an arithmetic number, because the mean of its divisors is an integer number (159945816).

Almost surely, 2^638747399 is an apocalyptic number.

638747399 is a deficient number, since it is larger than the sum of its proper divisors (1035865).

638747399 is a wasteful number, since it uses less digits than its factorization.

638747399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1035864.

The product of its digits is 6858432, while the sum is 56.

The square root of 638747399 is about 25273.4524550960. The cubic root of 638747399 is about 861.2112906895.

The spelling of 638747399 in words is "six hundred thirty-eight million, seven hundred forty-seven thousand, three hundred ninety-nine".