21709568997 has 8 divisors (see below), whose sum is σ = 32162324480. Its totient is φ = 14473045980.

The previous prime is 21709568963. The next prime is 21709568999. The reversal of 21709568997 is 79986590712.

It is not a de Polignac number, because 21709568997 - 2¹⁶ = 21709503461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21709568999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 402029029 + ... + 402029082.

It is an arithmetic number, because the mean of its divisors is an integer number (4020290560).

Almost surely, 2^21709568997 is an apocalyptic number.

21709568997 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21709568997 is a deficient number, since it is larger than the sum of its proper divisors (10452755483).

21709568997 is an equidigital number, since it uses as much as digits as its factorization.

21709568997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 804058120 (or 804058114 counting only the distinct ones).

The product of its (nonzero) digits is 17146080, while the sum is 63.

The spelling of 21709568997 in words is "twenty-one billion, seven hundred nine million, five hundred sixty-eight thousand, nine hundred ninety-seven".