9121986721 has 8 divisors (see below), whose sum is σ = 9520787304. Its totient is φ = 8731582080.

The previous prime is 9121986689. The next prime is 9121986733. The reversal of 9121986721 is 1276891219.

It can be written as a sum of positive squares in 4 ways, for example, as 1291683600 + 7830303121 = 35940^2 + 88489^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 9121986721 - 2⁵ = 9121986689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9121986521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2096766 + ... + 2101111.

It is an arithmetic number, because the mean of its divisors is an integer number (1190098413).

Almost surely, 2^9121986721 is an apocalyptic number.

It is an amenable number.

9121986721 is a deficient number, since it is larger than the sum of its proper divisors (398800583).

9121986721 is a wasteful number, since it uses less digits than its factorization.

9121986721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4197971.

The product of its digits is 108864, while the sum is 46.

The square root of 9121986721 is about 95509.0923472734. The cubic root of 9121986721 is about 2089.4395543274.

The spelling of 9121986721 in words is "nine billion, one hundred twenty-one million, nine hundred eighty-six thousand, seven hundred twenty-one".