21552957617 has 2 divisors, whose sum is σ = 21552957618. Its totient is φ = 21552957616.

The previous prime is 21552957589. The next prime is 21552957619. The reversal of 21552957617 is 71675925512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19868593936 + 1684363681 = 140956^2 + 41041^2 .

It is a cyclic number.

It is not a de Polignac number, because 21552957617 - 2²⁶ = 21485848753 is a prime.

Together with 21552957619, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21552957619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10776478808 + 10776478809.

It is an arithmetic number, because the mean of its divisors is an integer number (10776478809).

Almost surely, 2^21552957617 is an apocalyptic number.

It is an amenable number.

21552957617 is a deficient number, since it is larger than the sum of its proper divisors (1).

21552957617 is an equidigital number, since it uses as much as digits as its factorization.

21552957617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1323000, while the sum is 50.

The spelling of 21552957617 in words is "twenty-one billion, five hundred fifty-two million, nine hundred fifty-seven thousand, six hundred seventeen".