21121021218 has 16 divisors (see below), whose sum is σ = 46082228256. Its totient is φ = 6400309440.

The previous prime is 21121021211. The next prime is 21121021231. The reversal of 21121021218 is 81212012112.

It is a junction number, because it is equal to n+sod(n) for n = 21121021194 and 21121021203.

It is not an unprimeable number, because it can be changed into a prime (21121021211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 160007671 + ... + 160007802.

It is an arithmetic number, because the mean of its divisors is an integer number (2880139266).

Almost surely, 2^21121021218 is an apocalyptic number.

21121021218 is an abundant number, since it is smaller than the sum of its proper divisors (24961207038).

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

21121021218 is a wasteful number, since it uses less digits than its factorization.

21121021218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320015489.

The product of its (nonzero) digits is 128, while the sum is 21.

The spelling of 21121021218 in words is "twenty-one billion, one hundred twenty-one million, twenty-one thousand, two hundred eighteen".