9120721 has 4 divisors (see below), whose sum is σ = 9657252. Its totient is φ = 8584192.

The previous prime is 9120701. The next prime is 9120739. The reversal of 9120721 is 1270219.

9120721 = 2135² + 2136².

9120721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1270219 = 317 ⋅4007.

It can be written as a sum of positive squares in 2 ways, for example, as 4558225 + 4562496 = 2135^2 + 2136^2 .

It is a cyclic number.

It is not a de Polignac number, because 9120721 - 2¹³ = 9112529 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 9120692 and 9120701.

It is not an unprimeable number, because it can be changed into a prime (9120701) 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, 268240 + ... + 268273.

It is an arithmetic number, because the mean of its divisors is an integer number (2414313).

Almost surely, 2^9120721 is an apocalyptic number.

9120721 is the 2136-th centered square number.

It is an amenable number.

9120721 is a deficient number, since it is larger than the sum of its proper divisors (536531).

9120721 is a wasteful number, since it uses less digits than its factorization.

9120721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 536530.

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 9120721 is about 3020.0531452277. The cubic root of 9120721 is about 208.9342909816.

The spelling of 9120721 in words is "nine million, one hundred twenty thousand, seven hundred twenty-one".