21343121549 has 2 divisors, whose sum is σ = 21343121550. Its totient is φ = 21343121548.

The previous prime is 21343121491. The next prime is 21343121573. The reversal of 21343121549 is 94512134312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20875048324 + 468073225 = 144482^2 + 21635^2 .

It is a cyclic number.

It is not a de Polignac number, because 21343121549 - 2¹⁶ = 21343056013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21343121599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10671560774 + 10671560775.

It is an arithmetic number, because the mean of its divisors is an integer number (10671560775).

Almost surely, 2^21343121549 is an apocalyptic number.

It is an amenable number.

21343121549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21343121549 is an equidigital number, since it uses as much as digits as its factorization.

21343121549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 35.

The spelling of 21343121549 in words is "twenty-one billion, three hundred forty-three million, one hundred twenty-one thousand, five hundred forty-nine".