9725991 has 16 divisors (see below), whose sum is σ = 14636160. Its totient is φ = 5690720.

The previous prime is 9725959. The next prime is 9726001. The reversal of 9725991 is 1995279.

It is a cyclic number.

It is not a de Polignac number, because 9725991 - 2⁵ = 9725959 is a prime.

It is a super-3 number, since 3×9725991³ (a number of 22 digits) contains 333 as substring.

Its product of digits (51030) is a multiple of the sum of its prime divisors (10206).

It is a nialpdrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9725951) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4125 + ... + 6038.

It is an arithmetic number, because the mean of its divisors is an integer number (914760).

Almost surely, 2^9725991 is an apocalyptic number.

9725991 is a deficient number, since it is larger than the sum of its proper divisors (4910169).

9725991 is a wasteful number, since it uses less digits than its factorization.

9725991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10206.

The product of its digits is 51030, while the sum is 42.

The square root of 9725991 is about 3118.6521126923. The cubic root of 9725991 is about 213.4574356588.

The spelling of 9725991 in words is "nine million, seven hundred twenty-five thousand, nine hundred ninety-one".