21009571220747 has 2 divisors, whose sum is σ = 21009571220748. Its totient is φ = 21009571220746.

The previous prime is 21009571220641. The next prime is 21009571220791. The reversal of 21009571220747 is 74702217590012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21009571220747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21009571220797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10504785610373 + 10504785610374.

It is an arithmetic number, because the mean of its divisors is an integer number (10504785610374).

Almost surely, 2^{21009571220747} is an apocalyptic number.

21009571220747 is a deficient number, since it is larger than the sum of its proper divisors (1).

21009571220747 is an equidigital number, since it uses as much as digits as its factorization.

21009571220747 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 493920, while the sum is 47.

The spelling of 21009571220747 in words is "twenty-one trillion, nine billion, five hundred seventy-one million, two hundred twenty thousand, seven hundred forty-seven".