9917820 has 72 divisors (see below), whose sum is σ = 32825520. Its totient is φ = 2403840.

The previous prime is 9917779. The next prime is 9917827. The reversal of 9917820 is 287199.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9917827) 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, 525 + ... + 4484.

It is an arithmetic number, because the mean of its divisors is an integer number (455910).

Almost surely, 2^9917820 is an apocalyptic number.

9917820 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 9917820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (16412760).

9917820 is an abundant number, since it is smaller than the sum of its proper divisors (22907700).

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

9917820 is a wasteful number, since it uses less digits than its factorization.

9917820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5035 (or 5030 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 9917820 is about 3149.2570552433. The cubic root of 9917820 is about 214.8516734290.

The spelling of 9917820 in words is "nine million, nine hundred seventeen thousand, eight hundred twenty".