21089997709 has 16 divisors (see below), whose sum is σ = 23698312704. Its totient is φ = 18602766000.

The previous prime is 21089997641. The next prime is 21089997769. The reversal of 21089997709 is 90779998012.

It is a cyclic number.

It is not a de Polignac number, because 21089997709 - 2⁹ = 21089997197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21089997769) 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 in 15 ways as a sum of consecutive naturals, for example, 76219 + ... + 219064.

It is an arithmetic number, because the mean of its divisors is an integer number (1481144544).

Almost surely, 2^21089997709 is an apocalyptic number.

It is an amenable number.

21089997709 is a deficient number, since it is larger than the sum of its proper divisors (2608314995).

21089997709 is a wasteful number, since it uses less digits than its factorization.

21089997709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295488.

The product of its (nonzero) digits is 5143824, while the sum is 61.

The spelling of 21089997709 in words is "twenty-one billion, eighty-nine million, nine hundred ninety-seven thousand, seven hundred nine".