21545044489 has 2 divisors, whose sum is σ = 21545044490. Its totient is φ = 21545044488.

The previous prime is 21545044487. The next prime is 21545044561. The reversal of 21545044489 is 98444054512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16057198089 + 5487846400 = 126717^2 + 74080^2 .

It is a cyclic number.

It is not a de Polignac number, because 21545044489 - 2¹ = 21545044487 is a prime.

It is a super-2 number, since 2×21545044489² (a number of 21 digits) contains 22 as substring.

Together with 21545044487, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21545044487) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772522244 + 10772522245.

It is an arithmetic number, because the mean of its divisors is an integer number (10772522245).

Almost surely, 2^21545044489 is an apocalyptic number.

It is an amenable number.

21545044489 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545044489 is an equidigital number, since it uses as much as digits as its factorization.

21545044489 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 921600, while the sum is 46.

The spelling of 21545044489 in words is "twenty-one billion, five hundred forty-five million, forty-four thousand, four hundred eighty-nine".