21508331633 has 2 divisors, whose sum is σ = 21508331634. Its totient is φ = 21508331632.

The previous prime is 21508331629. The next prime is 21508331639. The reversal of 21508331633 is 33613380512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15773601649 + 5734729984 = 125593^2 + 75728^2 .

It is a cyclic number.

It is not a de Polignac number, because 21508331633 - 2² = 21508331629 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21508331593 and 21508331602.

It is not a weakly prime, because it can be changed into another prime (21508331639) 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, 10754165816 + 10754165817.

It is an arithmetic number, because the mean of its divisors is an integer number (10754165817).

Almost surely, 2^21508331633 is an apocalyptic number.

It is an amenable number.

21508331633 is a deficient number, since it is larger than the sum of its proper divisors (1).

21508331633 is an equidigital number, since it uses as much as digits as its factorization.

21508331633 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 35.

The spelling of 21508331633 in words is "twenty-one billion, five hundred eight million, three hundred thirty-one thousand, six hundred thirty-three".