9721890 has 32 divisors (see below), whose sum is σ = 25925760. Its totient is φ = 2592432.

The previous prime is 9721883. The next prime is 9721891. The reversal of 9721890 is 981279.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (9721891) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17734 + ... + 18273.

It is an arithmetic number, because the mean of its divisors is an integer number (810180).

Almost surely, 2^9721890 is an apocalyptic number.

9721890 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

9721890 is an abundant number, since it is smaller than the sum of its proper divisors (16203870).

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

9721890 is a wasteful number, since it uses less digits than its factorization.

9721890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36023 (or 36017 counting only the distinct ones).

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

The square root of 9721890 is about 3117.9945477823. The cubic root of 9721890 is about 213.4274297358.

The spelling of 9721890 in words is "nine million, seven hundred twenty-one thousand, eight hundred ninety".