21165653603 has 2 divisors, whose sum is σ = 21165653604. Its totient is φ = 21165653602.

The previous prime is 21165653539. The next prime is 21165653659. The reversal of 21165653603 is 30635656112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21165653603 - 2⁶ = 21165653539 is a prime.

It is not a weakly prime, because it can be changed into another prime (21165623603) 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, 10582826801 + 10582826802.

It is an arithmetic number, because the mean of its divisors is an integer number (10582826802).

Almost surely, 2^21165653603 is an apocalyptic number.

21165653603 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165653603 is an equidigital number, since it uses as much as digits as its factorization.

21165653603 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 97200, while the sum is 38.

The spelling of 21165653603 in words is "twenty-one billion, one hundred sixty-five million, six hundred fifty-three thousand, six hundred three".