9997920 has 144 divisors (see below), whose sum is σ = 35026992. Its totient is φ = 2595840.

The previous prime is 9997913. The next prime is 9997927. The reversal of 9997920 is 297999.

It is an interprime number because it is at equal distance from previous prime (9997913) and next prime (9997927).

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9997927) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 76255 + ... + 76385.

It is an arithmetic number, because the mean of its divisors is an integer number (243243).

Almost surely, 2^9997920 is an apocalyptic number.

9997920 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9997920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17513496).

9997920 is an abundant number, since it is smaller than the sum of its proper divisors (25029072).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9997920 is a wasteful number, since it uses less digits than its factorization.

9997920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205 (or 194 counting only the distinct ones).

The product of its (nonzero) digits is 91854, while the sum is 45.

The square root of 9997920 is about 3161.9487661883. The cubic root of 9997920 is about 215.4285305536.

It can be divided in two parts, 99979 and 20, that added together give a palindrome (99999).

The spelling of 9997920 in words is "nine million, nine hundred ninety-seven thousand, nine hundred twenty".