21001001211 has 48 divisors (see below), whose sum is σ = 31880808960. Its totient is φ = 13308079680.

The previous prime is 21001001209. The next prime is 21001001227. The reversal of 21001001211 is 11210010012.

It is a happy number.

It is not a de Polignac number, because 21001001211 - 2¹ = 21001001209 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21001001193 and 21001001202.

It is not an unprimeable number, because it can be changed into a prime (21001001291) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3289020 + ... + 3295398.

It is an arithmetic number, because the mean of its divisors is an integer number (664183520).

Almost surely, 2^21001001211 is an apocalyptic number.

21001001211 is a deficient number, since it is larger than the sum of its proper divisors (10879807749).

21001001211 is a wasteful number, since it uses less digits than its factorization.

21001001211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6656 (or 6653 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21001001211 its reverse (11210010012), we get a palindrome (32211011223).

It can be divided in two parts, 210010012 and 11, that multiplied together give a palindrome (2310110132).

The spelling of 21001001211 in words is "twenty-one billion, one million, one thousand, two hundred eleven".