9721890919 has 4 divisors (see below), whose sum is σ = 10469728696. Its totient is φ = 8974053144.

The previous prime is 9721890889. The next prime is 9721890923. The reversal of 9721890919 is 9190981279.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 9721890919 - 2⁹ = 9721890407 is a prime.

It is a super-2 number, since 2×9721890919² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9721890919.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9721890019) 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, 373918869 + ... + 373918894.

It is an arithmetic number, because the mean of its divisors is an integer number (2617432174).

Almost surely, 2^9721890919 is an apocalyptic number.

9721890919 is a deficient number, since it is larger than the sum of its proper divisors (747837777).

9721890919 is a wasteful number, since it uses less digits than its factorization.

9721890919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 747837776.

The product of its (nonzero) digits is 734832, while the sum is 55.

The square root of 9721890919 is about 98599.6496900471. The cubic root of 9721890919 is about 2134.2743646083.

The spelling of 9721890919 in words is "nine billion, seven hundred twenty-one million, eight hundred ninety thousand, nine hundred nineteen".