9991026 has 20 divisors (see below), whose sum is σ = 22387662. Its totient is φ = 3330288.

The previous prime is 9990997. The next prime is 9991027. The reversal of 9991026 is 6201999.

9991026 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 5517801 + 4473225 = 2349^2 + 2115^2 .

It is not an unprimeable number, because it can be changed into a prime (9991027) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 30675 + ... + 30998.

Almost surely, 2^9991026 is an apocalyptic number.

9991026 is an abundant number, since it is smaller than the sum of its proper divisors (12396636).

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

9991026 is a wasteful number, since it uses less digits than its factorization.

9991026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61687 (or 61678 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 36.

The square root of 9991026 is about 3160.8584277060. The cubic root of 9991026 is about 215.3790033925.

It can be divided in two parts, 999 and 1026, that added together give a square (2025 = 45²).

The spelling of 9991026 in words is "nine million, nine hundred ninety-one thousand, twenty-six".