9999990 has 256 divisors, whose sum is σ = 36771840. Its totient is φ = 1866240.

The previous prime is 9999973. The next prime is 9999991. The reversal of 9999990 is 999999.

9999990 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9999991) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 270252 + ... + 270288.

It is an arithmetic number, because the mean of its divisors is an integer number (143640).

Almost surely, 2^9999990 is an apocalyptic number.

9999990 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 9999990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18385920).

9999990 is an abundant number, since it is smaller than the sum of its proper divisors (26771850).

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

9999990 is a wasteful number, since it uses less digits than its factorization.

9999990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 78 counting only the distinct ones).

The product of its (nonzero) digits is 531441, while the sum is 54.

The square root of 9999990 is about 3162.2760790292. The cubic root of 9999990 is about 215.4433971887.

It can be divided in two parts, 9 and 999990, that added together give a palindrome (999999).

The spelling of 9999990 in words is "nine million, nine hundred ninety-nine thousand, nine hundred ninety".