21708824049 has 18 divisors (see below), whose sum is σ = 34466996018. Its totient is φ = 13156862400.

The previous prime is 21708824047. The next prime is 21708824063. The reversal of 21708824049 is 94042880712.

It can be written as a sum of positive squares in only one way, i.e., 21613410225 + 95413824 = 147015^2 + 9768^2 .

It is not a de Polignac number, because 21708824049 - 2¹ = 21708824047 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21708823995 and 21708824013.

It is not an unprimeable number, because it can be changed into a prime (21708824047) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 9966232 + ... + 9968409.

Almost surely, 2^21708824049 is an apocalyptic number.

It is an amenable number.

21708824049 is a deficient number, since it is larger than the sum of its proper divisors (12758171969).

21708824049 is a wasteful number, since it uses less digits than its factorization.

21708824049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19934669 (or 19934655 counting only the distinct ones).

The product of its (nonzero) digits is 258048, while the sum is 45.

The spelling of 21708824049 in words is "twenty-one billion, seven hundred eight million, eight hundred twenty-four thousand, forty-nine".