21156211718 has 64 divisors (see below), whose sum is σ = 34237728000. Its totient is φ = 9786801024.

The previous prime is 21156211717. The next prime is 21156211753. The reversal of 21156211718 is 81711265112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21156211717) 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 31 ways as a sum of consecutive naturals, for example, 28627793 + ... + 28628531.

It is an arithmetic number, because the mean of its divisors is an integer number (534964500).

Almost surely, 2^21156211718 is an apocalyptic number.

21156211718 is a deficient number, since it is larger than the sum of its proper divisors (13081516282).

21156211718 is a wasteful number, since it uses less digits than its factorization.

21156211718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1029.

The product of its digits is 6720, while the sum is 35.

The spelling of 21156211718 in words is "twenty-one billion, one hundred fifty-six million, two hundred eleven thousand, seven hundred eighteen".