21212103121309 has 2 divisors, whose sum is σ = 21212103121310. Its totient is φ = 21212103121308.

The previous prime is 21212103121193. The next prime is 21212103121337. The reversal of 21212103121309 is 90312130121212.

It is an a-pointer prime, because the next prime (21212103121337) can be obtained adding 21212103121309 to its sum of digits (28).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20371953060900 + 840150060409 = 4513530^2 + 916597^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212103121309 - 2²¹ = 21212101024157 is a prime.

It is a super-3 number, since 3×21212103121309³ (a number of 41 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21212103121009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606051560654 + 10606051560655.

It is an arithmetic number, because the mean of its divisors is an integer number (10606051560655).

Almost surely, 2^{21212103121309} is an apocalyptic number.

It is an amenable number.

21212103121309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212103121309 is an equidigital number, since it uses as much as digits as its factorization.

21212103121309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 28.

The spelling of 21212103121309 in words is "twenty-one trillion, two hundred twelve billion, one hundred three million, one hundred twenty-one thousand, three hundred nine".