638355728855 has 16 divisors (see below), whose sum is σ = 824979923040. Its totient is φ = 471385208448.

The previous prime is 638355728827. The next prime is 638355728873. The reversal of 638355728855 is 558827553836.

It is a cyclic number.

It is not a de Polignac number, because 638355728855 - 2¹⁰ = 638355727831 is a prime.

It is a super-2 number, since 2×638355728855² (a number of 24 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (65) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (65).

It is a junction number, because it is equal to n+sod(n) for n = 638355728791 and 638355728800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1982501 + ... + 2281889.

It is an arithmetic number, because the mean of its divisors is an integer number (51561245190).

Almost surely, 2^638355728855 is an apocalyptic number.

638355728855 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

638355728855 is a deficient number, since it is larger than the sum of its proper divisors (186624194185).

638355728855 is a wasteful number, since it uses less digits than its factorization.

638355728855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332210.

The product of its digits is 241920000, while the sum is 65.

The spelling of 638355728855 in words is "six hundred thirty-eight billion, three hundred fifty-five million, seven hundred twenty-eight thousand, eight hundred fifty-five".