21120213155549 has 2 divisors, whose sum is σ = 21120213155550. Its totient is φ = 21120213155548.

The previous prime is 21120213155519. The next prime is 21120213155551. The reversal of 21120213155549 is 94555131202112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20065293124900 + 1054920030649 = 4479430^2 + 1027093^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21120213155549 is a prime.

Together with 21120213155551, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120213155519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560106577774 + 10560106577775.

It is an arithmetic number, because the mean of its divisors is an integer number (10560106577775).

Almost surely, 2^{21120213155549} is an apocalyptic number.

It is an amenable number.

21120213155549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120213155549 is an equidigital number, since it uses as much as digits as its factorization.

21120213155549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 108000, while the sum is 41.

The spelling of 21120213155549 in words is "twenty-one trillion, one hundred twenty billion, two hundred thirteen million, one hundred fifty-five thousand, five hundred forty-nine".