21717540553 has 2 divisors, whose sum is σ = 21717540554. Its totient is φ = 21717540552.

The previous prime is 21717540529. The next prime is 21717540629. The reversal of 21717540553 is 35504571712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21012531849 + 705008704 = 144957^2 + 26552^2 .

It is a cyclic number.

It is not a de Polignac number, because 21717540553 - 2³³ = 13127605961 is a prime.

It is not a weakly prime, because it can be changed into another prime (21717540653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858770276 + 10858770277.

It is an arithmetic number, because the mean of its divisors is an integer number (10858770277).

Almost surely, 2^21717540553 is an apocalyptic number.

It is an amenable number.

21717540553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717540553 is an equidigital number, since it uses as much as digits as its factorization.

21717540553 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 147000, while the sum is 40.

The spelling of 21717540553 in words is "twenty-one billion, seven hundred seventeen million, five hundred forty thousand, five hundred fifty-three".