9721605663 has 160 divisors (see below), whose sum is σ = 18821637120. Its totient is φ = 4854090240.

The previous prime is 9721605629. The next prime is 9721605697. The reversal of 9721605663 is 3665061279.

9721605663 is a `hidden beast` number, since 9 + 7 + 21 + 60 + 566 + 3 = 666.

It is an interprime number because it is at equal distance from previous prime (9721605629) and next prime (9721605697).

It is not a de Polignac number, because 9721605663 - 2¹⁷ = 9721474591 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9721605263) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 23769003 + ... + 23769411.

It is an arithmetic number, because the mean of its divisors is an integer number (117635232).

Almost surely, 2^9721605663 is an apocalyptic number.

9721605663 is a deficient number, since it is larger than the sum of its proper divisors (9100031457).

9721605663 is a wasteful number, since it uses less digits than its factorization.

9721605663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579 (or 570 counting only the distinct ones).

The product of its (nonzero) digits is 408240, while the sum is 45.

The square root of 9721605663 is about 98598.2031428565. The cubic root of 9721605663 is about 2134.2534900505.

The spelling of 9721605663 in words is "nine billion, seven hundred twenty-one million, six hundred five thousand, six hundred sixty-three".