9801721789 has 4 divisors (see below), whose sum is σ = 9812073024. Its totient is φ = 9791370556.

The previous prime is 9801721759. The next prime is 9801721799. The reversal of 9801721789 is 9871271089.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9871271089 = 12853 ⋅768013.

It is a cyclic number.

It is not a de Polignac number, because 9801721789 - 2¹⁷ = 9801590717 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 (9801721759) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5174197 + ... + 5176090.

It is an arithmetic number, because the mean of its divisors is an integer number (2453018256).

Almost surely, 2^9801721789 is an apocalyptic number.

It is an amenable number.

9801721789 is a deficient number, since it is larger than the sum of its proper divisors (10351235).

9801721789 is a wasteful number, since it uses less digits than its factorization.

9801721789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10351234.

The product of its (nonzero) digits is 508032, while the sum is 52.

The square root of 9801721789 is about 99003.6453318765. The cubic root of 9801721789 is about 2140.1002798235.

The spelling of 9801721789 in words is "nine billion, eight hundred one million, seven hundred twenty-one thousand, seven hundred eighty-nine".