21210110101 has 4 divisors (see below), whose sum is σ = 21210452172. Its totient is φ = 21209768032.

The previous prime is 21210110087. The next prime is 21210110111. The reversal of 21210110101 is 10101101212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10388909476 + 10821200625 = 101926^2 + 104025^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210110101 - 2²¹ = 21208012949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210110111) 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, 49006 + ... + 211711.

It is an arithmetic number, because the mean of its divisors is an integer number (5302613043).

Almost surely, 2^21210110101 is an apocalyptic number.

It is an amenable number.

21210110101 is a deficient number, since it is larger than the sum of its proper divisors (342071).

21210110101 is an equidigital number, since it uses as much as digits as its factorization.

21210110101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342070.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21210110101 its reverse (10101101212), we get a palindrome (31311211313).

The spelling of 21210110101 in words is "twenty-one billion, two hundred ten million, one hundred ten thousand, one hundred one".