9921534561 has 20 divisors (see below), whose sum is σ = 14826815344. Its totient is φ = 6611787000.

The previous prime is 9921534559. The next prime is 9921534569. The reversal of 9921534561 is 1654351299.

9921534561 is a `hidden beast` number, since 99 + 21 + 534 + 5 + 6 + 1 = 666.

It is not a de Polignac number, because 9921534561 - 2¹ = 9921534559 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (9921534569) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 198786 + ... + 243636.

Almost surely, 2^9921534561 is an apocalyptic number.

It is an amenable number.

9921534561 is a deficient number, since it is larger than the sum of its proper divisors (4905280783).

9921534561 is a wasteful number, since it uses less digits than its factorization.

9921534561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47594 (or 47585 counting only the distinct ones).

The product of its digits is 291600, while the sum is 45.

The square root of 9921534561 is about 99606.9001676089. The cubic root of 9921534561 is about 2148.7849316800.

The spelling of 9921534561 in words is "nine billion, nine hundred twenty-one million, five hundred thirty-four thousand, five hundred sixty-one".