21212100031 has 2 divisors, whose sum is σ = 21212100032. Its totient is φ = 21212100030.

The previous prime is 21212100017. The next prime is 21212100089. The reversal of 21212100031 is 13000121212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21212100031 - 2⁵ = 21212099999 is a prime.

It is a super-3 number, since 3×21212100031³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 21212099984 and 21212100020.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21212100001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606050015 + 10606050016.

It is an arithmetic number, because the mean of its divisors is an integer number (10606050016).

Almost surely, 2^21212100031 is an apocalyptic number.

21212100031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212100031 is an equidigital number, since it uses as much as digits as its factorization.

21212100031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21212100031 its reverse (13000121212), we get a palindrome (34212221243).

The spelling of 21212100031 in words is "twenty-one billion, two hundred twelve million, one hundred thousand, thirty-one".