21111211001 has 4 divisors (see below), whose sum is σ = 21378441600. Its totient is φ = 20843980404.

The previous prime is 21111210977. The next prime is 21111211003. The reversal of 21111211001 is 10011211112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111211001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111211003) 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, 133615181 + ... + 133615338.

It is an arithmetic number, because the mean of its divisors is an integer number (5344610400).

Almost surely, 2^21111211001 is an apocalyptic number.

It is an amenable number.

21111211001 is a deficient number, since it is larger than the sum of its proper divisors (267230599).

21111211001 is an equidigital number, since it uses as much as digits as its factorization.

21111211001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267230598.

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

Adding to 21111211001 its reverse (10011211112), we get a palindrome (31122422113).

The spelling of 21111211001 in words is "twenty-one billion, one hundred eleven million, two hundred eleven thousand, one".