638805358009 has 27 divisors (see below), whose sum is σ = 804750325263. Its totient is φ = 505370868912.

The previous prime is 638805358007. The next prime is 638805358021. The reversal of 638805358009 is 900853508836.

The square root of 638805358009 is 799253.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 94497834025 + 544307523984 = 307405^2 + 737772^2 .

It is not a de Polignac number, because 638805358009 - 2¹ = 638805358007 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638805358007) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 72727632 + ... + 72736414.

Almost surely, 2^638805358009 is an apocalyptic number.

638805358009 is the 799253-rd square number.

638805358009 is the 399627-th centered octagonal number.

It is an amenable number.

638805358009 is a deficient number, since it is larger than the sum of its proper divisors (165944967254).

638805358009 is an frugal number, since it uses more digits than its factorization.

638805358009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17606 (or 8803 counting only the distinct ones).

The product of its (nonzero) digits is 6220800, while the sum is 55.

The spelling of 638805358009 in words is "six hundred thirty-eight billion, eight hundred five million, three hundred fifty-eight thousand, nine".