21305518017018 has 16 divisors (see below), whose sum is σ = 42812984074656. Its totient is φ = 7068181332240.

The previous prime is 21305518016947. The next prime is 21305518017029. The reversal of 21305518017018 is 81071081550312.

It is a super-2 number, since 2×21305518017018² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8414500321 + ... + 8414502852.

It is an arithmetic number, because the mean of its divisors is an integer number (2675811504666).

Almost surely, 2^{21305518017018} is an apocalyptic number.

21305518017018 is an abundant number, since it is smaller than the sum of its proper divisors (21507466057638).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21305518017018 is a wasteful number, since it uses less digits than its factorization.

21305518017018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16829003389.

The product of its (nonzero) digits is 67200, while the sum is 42.

The spelling of 21305518017018 in words is "twenty-one trillion, three hundred five billion, five hundred eighteen million, seventeen thousand, eighteen".