21044817121 has 4 divisors (see below), whose sum is σ = 21770500500. Its totient is φ = 20319133744.

The previous prime is 21044816977. The next prime is 21044817133. The reversal of 21044817121 is 12171844012.

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 4874134225 + 16170682896 = 69815^2 + 127164^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21044817121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21044817421) 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, 362841646 + ... + 362841703.

It is an arithmetic number, because the mean of its divisors is an integer number (5442625125).

Almost surely, 2^21044817121 is an apocalyptic number.

It is an amenable number.

21044817121 is a deficient number, since it is larger than the sum of its proper divisors (725683379).

21044817121 is an equidigital number, since it uses as much as digits as its factorization.

21044817121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 725683378.

The product of its (nonzero) digits is 3584, while the sum is 31.

The spelling of 21044817121 in words is "twenty-one billion, forty-four million, eight hundred seventeen thousand, one hundred twenty-one".