21149056549 has 4 divisors (see below), whose sum is σ = 21256412364. Its totient is φ = 21041700736.

The previous prime is 21149056547. The next prime is 21149056571. The reversal of 21149056549 is 94565094112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19039032324 + 2110024225 = 137982^2 + 45935^2 .

It is a cyclic number.

It is not a de Polignac number, because 21149056549 - 2¹ = 21149056547 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21149056499 and 21149056508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21149056543) 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 in 3 ways as a sum of consecutive naturals, for example, 53677612 + ... + 53678005.

It is an arithmetic number, because the mean of its divisors is an integer number (5314103091).

Almost surely, 2^21149056549 is an apocalyptic number.

It is an amenable number.

21149056549 is a deficient number, since it is larger than the sum of its proper divisors (107355815).

21149056549 is a wasteful number, since it uses less digits than its factorization.

21149056549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107355814.

The product of its (nonzero) digits is 388800, while the sum is 46.

The spelling of 21149056549 in words is "twenty-one billion, one hundred forty-nine million, fifty-six thousand, five hundred forty-nine".