21544142549 has 2 divisors, whose sum is σ = 21544142550. Its totient is φ = 21544142548.

The previous prime is 21544142539. The next prime is 21544142561. The reversal of 21544142549 is 94524144512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21416859025 + 127283524 = 146345^2 + 11282^2 .

It is a cyclic number.

It is not a de Polignac number, because 21544142549 - 2⁴ = 21544142533 is a prime.

It is a super-3 number, since 3×21544142549³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21544142539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772071274 + 10772071275.

It is an arithmetic number, because the mean of its divisors is an integer number (10772071275).

Almost surely, 2^21544142549 is an apocalyptic number.

It is an amenable number.

21544142549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21544142549 is an equidigital number, since it uses as much as digits as its factorization.

21544142549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 230400, while the sum is 41.

The spelling of 21544142549 in words is "twenty-one billion, five hundred forty-four million, one hundred forty-two thousand, five hundred forty-nine".