21506205447117 has 16 divisors (see below), whose sum is σ = 32111919482880. Its totient is φ = 14224576828896.

The previous prime is 21506205447059. The next prime is 21506205447121. The reversal of 21506205447117 is 71174450260512.

21506205447117 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 6 + 20 + 544 + 71 + 17 = 666.

It is not a de Polignac number, because 21506205447117 - 2¹¹ = 21506205445069 is a prime.

It is a super-2 number, since 2×21506205447117² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21506205447127) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3135926208 + ... + 3135933065.

It is an arithmetic number, because the mean of its divisors is an integer number (2006994967680).

Almost surely, 2^{21506205447117} is an apocalyptic number.

21506205447117 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21506205447117 is a deficient number, since it is larger than the sum of its proper divisors (10605714035763).

21506205447117 is a wasteful number, since it uses less digits than its factorization.

21506205447117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6271859409 (or 6271859403 counting only the distinct ones).

The product of its (nonzero) digits is 470400, while the sum is 45.

The spelling of 21506205447117 in words is "twenty-one trillion, five hundred six billion, two hundred five million, four hundred forty-seven thousand, one hundred seventeen".