21211221018 has 16 divisors (see below), whose sum is σ = 45685706976. Its totient is φ = 6526529520.

The previous prime is 21211220993. The next prime is 21211221019. The reversal of 21211221018 is 81012211212.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21211220985 and 21211221003.

It is not an unprimeable number, because it can be changed into a prime (21211221019) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135969288 + ... + 135969443.

It is an arithmetic number, because the mean of its divisors is an integer number (2855356686).

Almost surely, 2^21211221018 is an apocalyptic number.

21211221018 is an abundant number, since it is smaller than the sum of its proper divisors (24474485958).

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

21211221018 is a wasteful number, since it uses less digits than its factorization.

21211221018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271938749.

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

The spelling of 21211221018 in words is "twenty-one billion, two hundred eleven million, two hundred twenty-one thousand, eighteen".