21212101021 has 8 divisors (see below), whose sum is σ = 21562184664. Its totient is φ = 20862093120.

The previous prime is 21212100983. The next prime is 21212101039. The reversal of 21212101021 is 12010121212.

It can be written as a sum of positive squares in 4 ways, for example, as 1950547225 + 19261553796 = 44165^2 + 138786^2 .

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 21212101021 - 2¹⁵ = 21212068253 is a prime.

It is a super-3 number, since 3×21212101021³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212100992 and 21212101010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212101051) 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, 952611 + ... + 974623.

It is an arithmetic number, because the mean of its divisors is an integer number (2695273083).

Almost surely, 2^21212101021 is an apocalyptic number.

It is an amenable number.

21212101021 is a deficient number, since it is larger than the sum of its proper divisors (350083643).

21212101021 is a wasteful number, since it uses less digits than its factorization.

21212101021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37871.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21212101021 its reverse (12010121212), we get a palindrome (33222222233).

The spelling of 21212101021 in words is "twenty-one billion, two hundred twelve million, one hundred one thousand, twenty-one".