21111221101 has 4 divisors (see below), whose sum is σ = 21173866012. Its totient is φ = 21048576192.

The previous prime is 21111221083. The next prime is 21111221111. The reversal of 21111221101 is 10112211112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10558590025 + 10552631076 = 102755^2 + 102726^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111221101 - 2⁵ = 21111221069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111221111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31321950 + ... + 31322623.

It is an arithmetic number, because the mean of its divisors is an integer number (5293466503).

Almost surely, 2^21111221101 is an apocalyptic number.

It is an amenable number.

21111221101 is a deficient number, since it is larger than the sum of its proper divisors (62644911).

21111221101 is an equidigital number, since it uses as much as digits as its factorization.

21111221101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62644910.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21111221101 its reverse (10112211112), we get a palindrome (31223432213).

The spelling of 21111221101 in words is "twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, one hundred one".