21355555097 has 2 divisors, whose sum is σ = 21355555098. Its totient is φ = 21355555096.

The previous prime is 21355555051. The next prime is 21355555103. The reversal of 21355555097 is 79055555312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19576487056 + 1779068041 = 139916^2 + 42179^2 .

It is a cyclic number.

It is not a de Polignac number, because 21355555097 - 2¹⁴ = 21355538713 is a prime.

It is not a weakly prime, because it can be changed into another prime (21355558097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677777548 + 10677777549.

It is an arithmetic number, because the mean of its divisors is an integer number (10677777549).

Almost surely, 2^21355555097 is an apocalyptic number.

It is an amenable number.

21355555097 is a deficient number, since it is larger than the sum of its proper divisors (1).

21355555097 is an equidigital number, since it uses as much as digits as its factorization.

21355555097 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1181250, while the sum is 47.

The spelling of 21355555097 in words is "twenty-one billion, three hundred fifty-five million, five hundred fifty-five thousand, ninety-seven".