21655106663 has 2 divisors, whose sum is σ = 21655106664. Its totient is φ = 21655106662.

The previous prime is 21655106659. The next prime is 21655106687. The reversal of 21655106663 is 36660155612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21655106663 - 2² = 21655106659 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21655106663.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21655103663) 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, 10827553331 + 10827553332.

It is an arithmetic number, because the mean of its divisors is an integer number (10827553332).

Almost surely, 2^21655106663 is an apocalyptic number.

21655106663 is a deficient number, since it is larger than the sum of its proper divisors (1).

21655106663 is an equidigital number, since it uses as much as digits as its factorization.

21655106663 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 194400, while the sum is 41.

The spelling of 21655106663 in words is "twenty-one billion, six hundred fifty-five million, one hundred six thousand, six hundred sixty-three".