638409255939 has 64 divisors (see below), whose sum is σ = 1167844142080. Its totient is φ = 335646063360.

The previous prime is 638409255899. The next prime is 638409256003. The reversal of 638409255939 is 939552904836.

638409255939 is a `hidden beast` number, since 6 + 3 + 8 + 40 + 9 + 2 + 559 + 39 = 666.

It is not a de Polignac number, because 638409255939 - 2⁷ = 638409255811 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (638409257939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 331119 + ... + 1177479.

It is an arithmetic number, because the mean of its divisors is an integer number (18247564720).

Almost surely, 2^638409255939 is an apocalyptic number.

638409255939 is a deficient number, since it is larger than the sum of its proper divisors (529434886141).

638409255939 is a wasteful number, since it uses less digits than its factorization.

638409255939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 846697 (or 846691 counting only the distinct ones).

The product of its (nonzero) digits is 62985600, while the sum is 63.

The spelling of 638409255939 in words is "six hundred thirty-eight billion, four hundred nine million, two hundred fifty-five thousand, nine hundred thirty-nine".