21044340553 has 2 divisors, whose sum is σ = 21044340554. Its totient is φ = 21044340552.

The previous prime is 21044340539. The next prime is 21044340571. The reversal of 21044340553 is 35504344012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19764704569 + 1279635984 = 140587^2 + 35772^2 .

It is a cyclic number.

It is not a de Polignac number, because 21044340553 - 2¹⁷ = 21044209481 is a prime.

It is not a weakly prime, because it can be changed into another prime (21044340353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10522170276 + 10522170277.

It is an arithmetic number, because the mean of its divisors is an integer number (10522170277).

Almost surely, 2^21044340553 is an apocalyptic number.

It is an amenable number.

21044340553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21044340553 is an equidigital number, since it uses as much as digits as its factorization.

21044340553 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28800, while the sum is 31.

Adding to 21044340553 its reverse (35504344012), we get a palindrome (56548684565).

The spelling of 21044340553 in words is "twenty-one billion, forty-four million, three hundred forty thousand, five hundred fifty-three".