21212138819 has 2 divisors, whose sum is σ = 21212138820. Its totient is φ = 21212138818.

The previous prime is 21212138809. The next prime is 21212138863. The reversal of 21212138819 is 91883121212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212138819 is a prime.

It is a super-2 number, since 2×21212138819² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21212138809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606069409 + 10606069410.

It is an arithmetic number, because the mean of its divisors is an integer number (10606069410).

Almost surely, 2^21212138819 is an apocalyptic number.

21212138819 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212138819 is an equidigital number, since it uses as much as digits as its factorization.

21212138819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 38.

The spelling of 21212138819 in words is "twenty-one billion, two hundred twelve million, one hundred thirty-eight thousand, eight hundred nineteen".