21111212010221 has 8 divisors (see below), whose sum is σ = 21178729537560. Its totient is φ = 21043700273728.

The previous prime is 21111212010193. The next prime is 21111212010223. The reversal of 21111212010221 is 12201021211112.

It can be written as a sum of positive squares in 4 ways, for example, as 920613384196 + 20190598626025 = 959486^2 + 4493395^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21111212010221 - 2⁶ = 21111212010157 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21111212010221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111212010223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5914955 + ... + 8786871.

It is an arithmetic number, because the mean of its divisors is an integer number (2647341192195).

Almost surely, 2^{21111212010221} is an apocalyptic number.

It is an amenable number.

21111212010221 is a deficient number, since it is larger than the sum of its proper divisors (67517527339).

21111212010221 is a wasteful number, since it uses less digits than its factorization.

21111212010221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2895423.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21111212010221 its reverse (12201021211112), we get a palindrome (33312233221333).

The spelling of 21111212010221 in words is "twenty-one trillion, one hundred eleven billion, two hundred twelve million, ten thousand, two hundred twenty-one".