9990720 has 84 divisors (see below), whose sum is σ = 34373820. Its totient is φ = 2663424.

The previous prime is 9990689. The next prime is 9990727. The reversal of 9990720 is 270999.

It can be written as a sum of positive squares in 2 ways, for example, as 1557504 + 8433216 = 1248^2 + 2904^2 .

It is a super-2 number, since 2×9990720² = 199628972236800, which contains 22 as substring.

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

It is not an unprimeable number, because it can be changed into a prime (9990727) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1146 + ... + 4614.

Almost surely, 2^9990720 is an apocalyptic number.

9990720 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 9990720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17186910).

9990720 is an abundant number, since it is smaller than the sum of its proper divisors (24383100).

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

9990720 is a wasteful number, since it uses less digits than its factorization.

9990720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3492 (or 3479 counting only the distinct ones).

The product of its (nonzero) digits is 10206, while the sum is 36.

The square root of 9990720 is about 3160.8100227632. The cubic root of 9990720 is about 215.3768045310.

The spelling of 9990720 in words is "nine million, nine hundred ninety thousand, seven hundred twenty".