21044844649 has 4 divisors (see below), whose sum is σ = 21045826260. Its totient is φ = 21043863040.

The previous prime is 21044844643. The next prime is 21044844659. The reversal of 21044844649 is 94644844012.

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 19861828624 + 1183016025 = 140932^2 + 34395^2 .

It is a cyclic number.

It is not a de Polignac number, because 21044844649 - 2⁷ = 21044844521 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21044844599 and 21044844608.

It is not an unprimeable number, because it can be changed into a prime (21044844643) 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, 457912 + ... + 501769.

It is an arithmetic number, because the mean of its divisors is an integer number (5261456565).

Almost surely, 2^21044844649 is an apocalyptic number.

It is an amenable number.

21044844649 is a deficient number, since it is larger than the sum of its proper divisors (981611).

21044844649 is an equidigital number, since it uses as much as digits as its factorization.

21044844649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 981610.

The product of its (nonzero) digits is 884736, while the sum is 46.

The spelling of 21044844649 in words is "twenty-one billion, forty-four million, eight hundred forty-four thousand, six hundred forty-nine".