21212202121 has 8 divisors (see below), whose sum is σ = 23141649600. Its totient is φ = 19282932240.

The previous prime is 21212202101. The next prime is 21212202127. The reversal of 21212202121 is 12120221212.

It is a happy number.

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

It is not a de Polignac number, because 21212202121 - 2¹⁵ = 21212169353 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212202095 and 21212202104.

It is not an unprimeable number, because it can be changed into a prime (21212202127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 391215 + ... + 442123.

It is an arithmetic number, because the mean of its divisors is an integer number (2892706200).

Almost surely, 2^21212202121 is an apocalyptic number.

It is an amenable number.

21212202121 is a deficient number, since it is larger than the sum of its proper divisors (1929447479).

21212202121 is a wasteful number, since it uses less digits than its factorization.

21212202121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88799.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21212202121 its reverse (12120221212), we get a palindrome (33332423333).

The spelling of 21212202121 in words is "twenty-one billion, two hundred twelve million, two hundred two thousand, one hundred twenty-one".