9921784871 has 16 divisors (see below), whose sum is σ = 10178077728. Its totient is φ = 9668937600.

The previous prime is 9921784861. The next prime is 9921784903. The reversal of 9921784871 is 1784871299.

9921784871 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 9921784871 - 2¹⁰ = 9921783847 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9921784801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3233480 + ... + 3236546.

It is an arithmetic number, because the mean of its divisors is an integer number (636129858).

Almost surely, 2^9921784871 is an apocalyptic number.

9921784871 is a deficient number, since it is larger than the sum of its proper divisors (256292857).

9921784871 is a wasteful number, since it uses less digits than its factorization.

9921784871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3602.

The product of its digits is 2032128, while the sum is 56.

The square root of 9921784871 is about 99608.1566489412. The cubic root of 9921784871 is about 2148.8030020645.

The spelling of 9921784871 in words is "nine billion, nine hundred twenty-one million, seven hundred eighty-four thousand, eight hundred seventy-one".