21101021211 has 4 divisors (see below), whose sum is σ = 28134694952. Its totient is φ = 14067347472.

The previous prime is 21101021203. The next prime is 21101021243. The reversal of 21101021211 is 11212010112.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21101021211 - 2³ = 21101021203 is a prime.

It is a super-2 number, since 2×21101021211² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21101029211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3516836866 + ... + 3516836871.

It is an arithmetic number, because the mean of its divisors is an integer number (7033673738).

Almost surely, 2^21101021211 is an apocalyptic number.

21101021211 is a deficient number, since it is larger than the sum of its proper divisors (7033673741).

21101021211 is an equidigital number, since it uses as much as digits as its factorization.

21101021211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7033673740.

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

Adding to 21101021211 its reverse (11212010112), we get a palindrome (32313031323).

It can be divided in two parts, 211010 and 21211, that added together give a triangular number (232221 = T₆₈₁).

The spelling of 21101021211 in words is "twenty-one billion, one hundred one million, twenty-one thousand, two hundred eleven".