9992721 has 4 divisors (see below), whose sum is σ = 13323632. Its totient is φ = 6661812.

The previous prime is 9992713. The next prime is 9992737. The reversal of 9992721 is 1272999.

It is a happy number.

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.

It is not a de Polignac number, because 9992721 - 2³ = 9992713 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 9992721.

It is not an unprimeable number, because it can be changed into a prime (9992711) 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, 1665451 + ... + 1665456.

It is an arithmetic number, because the mean of its divisors is an integer number (3330908).

Almost surely, 2^9992721 is an apocalyptic number.

It is an amenable number.

9992721 is a deficient number, since it is larger than the sum of its proper divisors (3330911).

9992721 is a wasteful number, since it uses less digits than its factorization.

9992721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3330910.

The product of its digits is 20412, while the sum is 39.

The square root of 9992721 is about 3161.1265397007. The cubic root of 9992721 is about 215.3911825477.

The spelling of 9992721 in words is "nine million, nine hundred ninety-two thousand, seven hundred twenty-one".