21056605417 has 2 divisors, whose sum is σ = 21056605418. Its totient is φ = 21056605416.

The previous prime is 21056605333. The next prime is 21056605441. The reversal of 21056605417 is 71450665012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12378565081 + 8678040336 = 111259^2 + 93156^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21056605417 is a prime.

It is not a weakly prime, because it can be changed into another prime (21056605117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528302708 + 10528302709.

It is an arithmetic number, because the mean of its divisors is an integer number (10528302709).

Almost surely, 2^21056605417 is an apocalyptic number.

It is an amenable number.

21056605417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21056605417 is an equidigital number, since it uses as much as digits as its factorization.

21056605417 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 50400, while the sum is 37.

The spelling of 21056605417 in words is "twenty-one billion, fifty-six million, six hundred five thousand, four hundred seventeen".