21112111001 has 4 divisors (see below), whose sum is σ = 21510452772. Its totient is φ = 20713769232.

The previous prime is 21112110961. The next prime is 21112111019. The reversal of 21112111001 is 10011121112.

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 9301638025 + 11810472976 = 96445^2 + 108676^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112111001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112111021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 199170806 + ... + 199170911.

It is an arithmetic number, because the mean of its divisors is an integer number (5377613193).

Almost surely, 2^21112111001 is an apocalyptic number.

It is an amenable number.

21112111001 is a deficient number, since it is larger than the sum of its proper divisors (398341771).

21112111001 is an equidigital number, since it uses as much as digits as its factorization.

21112111001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398341770.

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 21112111001 its reverse (10011121112), we get a palindrome (31123232113).

It can be divided in two parts, 2111 and 2111001, that added together give a palindrome (2113112).

The spelling of 21112111001 in words is "twenty-one billion, one hundred twelve million, one hundred eleven thousand, one".