21108434709 has 16 divisors (see below), whose sum is σ = 28684497600. Its totient is φ = 13802495616.

The previous prime is 21108434707. The next prime is 21108434741. The reversal of 21108434709 is 90743480112.

It is not a de Polignac number, because 21108434709 - 2¹ = 21108434707 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21108434701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 542302 + ... + 579920.

It is an arithmetic number, because the mean of its divisors is an integer number (1792781100).

Almost surely, 2^21108434709 is an apocalyptic number.

It is an amenable number.

21108434709 is a deficient number, since it is larger than the sum of its proper divisors (7576062891).

21108434709 is a wasteful number, since it uses less digits than its factorization.

21108434709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41204.

The product of its (nonzero) digits is 48384, while the sum is 39.

The spelling of 21108434709 in words is "twenty-one billion, one hundred eight million, four hundred thirty-four thousand, seven hundred nine".