21040505489 has 2 divisors, whose sum is σ = 21040505490. Its totient is φ = 21040505488.

The previous prime is 21040505461. The next prime is 21040505503. The reversal of 21040505489 is 98450504012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19483413889 + 1557091600 = 139583^2 + 39460^2 .

It is a cyclic number.

It is not a de Polignac number, because 21040505489 - 2¹² = 21040501393 is a prime.

It is not a weakly prime, because it can be changed into another prime (21040505389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520252744 + 10520252745.

It is an arithmetic number, because the mean of its divisors is an integer number (10520252745).

Almost surely, 2^21040505489 is an apocalyptic number.

It is an amenable number.

21040505489 is a deficient number, since it is larger than the sum of its proper divisors (1).

21040505489 is an equidigital number, since it uses as much as digits as its factorization.

21040505489 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 57600, while the sum is 38.

The spelling of 21040505489 in words is "twenty-one billion, forty million, five hundred five thousand, four hundred eighty-nine".