21101221011 has 16 divisors (see below), whose sum is σ = 30582365184. Its totient is φ = 12864005664.

The previous prime is 21101220991. The next prime is 21101221021. The reversal of 21101221011 is 11012210112.

It is not a de Polignac number, because 21101221011 - 2⁷ = 21101220883 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21101221021) 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, 2524131 + ... + 2532476.

It is an arithmetic number, because the mean of its divisors is an integer number (1911397824).

Almost surely, 2^21101221011 is an apocalyptic number.

21101221011 is a deficient number, since it is larger than the sum of its proper divisors (9481144173).

21101221011 is a wasteful number, since it uses less digits than its factorization.

21101221011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5056730.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21101221011 its reverse (11012210112), we get a palindrome (32113431123).

It can be divided in two parts, 2 and 1101221011, that multiplied together give a palindrome (2202442022).

The spelling of 21101221011 in words is "twenty-one billion, one hundred one million, two hundred twenty-one thousand, eleven".