21774365549 has 2 divisors, whose sum is σ = 21774365550. Its totient is φ = 21774365548.

The previous prime is 21774365461. The next prime is 21774365573. The reversal of 21774365549 is 94556347712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18442998025 + 3331367524 = 135805^2 + 57718^2 .

It is a cyclic number.

It is not a de Polignac number, because 21774365549 - 2²⁸ = 21505930093 is a prime.

It is a super-2 number, since 2×21774365549² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21774365549.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21774365149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10887182774 + 10887182775.

It is an arithmetic number, because the mean of its divisors is an integer number (10887182775).

Almost surely, 2^21774365549 is an apocalyptic number.

It is an amenable number.

21774365549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21774365549 is an equidigital number, since it uses as much as digits as its factorization.

21774365549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6350400, while the sum is 53.

The spelling of 21774365549 in words is "twenty-one billion, seven hundred seventy-four million, three hundred sixty-five thousand, five hundred forty-nine".