9891820 has 12 divisors (see below), whose sum is σ = 20772864. Its totient is φ = 3956720.

The previous prime is 9891809. The next prime is 9891823. The reversal of 9891820 is 281989.

It is a self number, because there is not a number n which added to its sum of digits gives 9891820.

It is not an unprimeable number, because it can be changed into a prime (9891823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 247276 + ... + 247315.

It is an arithmetic number, because the mean of its divisors is an integer number (1731072).

Almost surely, 2^9891820 is an apocalyptic number.

It is an amenable number.

9891820 is an abundant number, since it is smaller than the sum of its proper divisors (10881044).

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

9891820 is a wasteful number, since it uses less digits than its factorization.

9891820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 494600 (or 494598 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 9891820 is about 3145.1263885574. The cubic root of 9891820 is about 214.6637614325.

It can be divided in two parts, 989 and 1820, that added together give a square (2809 = 53²).

The spelling of 9891820 in words is "nine million, eight hundred ninety-one thousand, eight hundred twenty".