21121211001 has 32 divisors (see below), whose sum is σ = 31150780416. Its totient is φ = 12623000000.

The previous prime is 21121210987. The next prime is 21121211011. The reversal of 21121211001 is 10011212112.

It is a cyclic number.

It is not a de Polignac number, because 21121211001 - 2⁹ = 21121210489 is a prime.

It is a super-2 number, since 2×21121211001² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21121211011) 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 31 ways as a sum of consecutive naturals, for example, 823960 + ... + 849206.

It is an arithmetic number, because the mean of its divisors is an integer number (973461888).

Almost surely, 2^21121211001 is an apocalyptic number.

It is an amenable number.

21121211001 is a deficient number, since it is larger than the sum of its proper divisors (10029569415).

21121211001 is a wasteful number, since it uses less digits than its factorization.

21121211001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25613.

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

Adding to 21121211001 its reverse (10011212112), we get a palindrome (31132423113).

It can be divided in two parts, 211 and 21211001, that added together give a palindrome (21211212).

The spelling of 21121211001 in words is "twenty-one billion, one hundred twenty-one million, two hundred eleven thousand, one".