21001212211 has 8 divisors (see below), whose sum is σ = 24454242144. Its totient is φ = 17661396480.

The previous prime is 21001212181. The next prime is 21001212233. The reversal of 21001212211 is 11221210012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21001212211 - 2⁵ = 21001212179 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001212191 and 21001212200.

It is not an unprimeable number, because it can be changed into a prime (21001212611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28303150 + ... + 28303891.

It is an arithmetic number, because the mean of its divisors is an integer number (3056780268).

Almost surely, 2^21001212211 is an apocalyptic number.

21001212211 is a deficient number, since it is larger than the sum of its proper divisors (3453029933).

21001212211 is an equidigital number, since it uses as much as digits as its factorization.

21001212211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56607101.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21001212211 its reverse (11221210012), we get a palindrome (32222422223).

The spelling of 21001212211 in words is "twenty-one billion, one million, two hundred twelve thousand, two hundred eleven".