2101212221 has 4 divisors (see below), whose sum is σ = 2145918912. Its totient is φ = 2056505532.

The previous prime is 2101212143. The next prime is 2101212229. The reversal of 2101212221 is 1222121012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2101212221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2101212196 and 2101212205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2101212229) 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, 22353275 + ... + 22353368.

It is an arithmetic number, because the mean of its divisors is an integer number (536479728).

Almost surely, 2^2101212221 is an apocalyptic number.

It is an amenable number.

2101212221 is a deficient number, since it is larger than the sum of its proper divisors (44706691).

2101212221 is an equidigital number, since it uses as much as digits as its factorization.

2101212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44706690.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 2101212221 is about 45838.9814568343. The cubic root of 2101212221 is about 1280.8255215519.

Adding to 2101212221 its reverse (1222121012), we get a palindrome (3323333233).

It can be divided in two parts, 21012 and 12221, that multiplied together give a palindrome (256787652).

The spelling of 2101212221 in words is "two billion, one hundred one million, two hundred twelve thousand, two hundred twenty-one".