9721989 has 18 divisors (see below), whose sum is σ = 14602770. Its totient is φ = 6225408.

The previous prime is 9721979. The next prime is 9721991. The reversal of 9721989 is 9891279.

It can be written as a sum of positive squares in 3 ways, for example, as 173889 + 9548100 = 417^2 + 3090^2 .

It is not a de Polignac number, because 9721989 - 2⁹ = 9721477 is a prime.

It is a super-2 number, since 2×9721989² = 189034140232242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9721919) 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, 50277 + ... + 50469.

It is an arithmetic number, because the mean of its divisors is an integer number (811265).

Almost surely, 2^9721989 is an apocalyptic number.

It is an amenable number.

9721989 is a deficient number, since it is larger than the sum of its proper divisors (4880781).

9721989 is a wasteful number, since it uses less digits than its factorization.

9721989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 421 (or 225 counting only the distinct ones).

The product of its digits is 81648, while the sum is 45.

The square root of 9721989 is about 3118.0104233309. The cubic root of 9721989 is about 213.4281541918.

The spelling of 9721989 in words is "nine million, seven hundred twenty-one thousand, nine hundred eighty-nine".