21211112212121 has 8 divisors (see below), whose sum is σ = 22931618474184. Its totient is φ = 19503303413760.

The previous prime is 21211112212117. The next prime is 21211112212127. The reversal of 21211112212121 is 12121221111212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 11583676110400 + 9627436101721 = 3403480^2 + 3102811^2 .

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 21211112212121 - 2² = 21211112212117 is a prime.

It is a super-2 number, since 2×21211112212121² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211112212093 and 21211112212102.

It is not an unprimeable number, because it can be changed into a prime (21211112212127) 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, 3174362450 + ... + 3174369131.

It is an arithmetic number, because the mean of its divisors is an integer number (2866452309273).

Almost surely, 2^{21211112212121} is an apocalyptic number.

It is an amenable number.

21211112212121 is a deficient number, since it is larger than the sum of its proper divisors (1720506262063).

21211112212121 is a wasteful number, since it uses less digits than its factorization.

21211112212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6348731851.

The product of its digits is 64, while the sum is 20.

Adding to 21211112212121 its reverse (12121221111212), we get a palindrome (33332333323333).

The spelling of 21211112212121 in words is "twenty-one trillion, two hundred eleven billion, one hundred twelve million, two hundred twelve thousand, one hundred twenty-one".