9871721910 has 96 divisors (see below), whose sum is σ = 26643550752. Its totient is φ = 2629843200.

The previous prime is 9871721843. The next prime is 9871721929. The reversal of 9871721910 is 191271789.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4618362 + ... + 4620498.

It is an arithmetic number, because the mean of its divisors is an integer number (277536987).

Almost surely, 2^9871721910 is an apocalyptic number.

9871721910 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 9871721910, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13321775376).

9871721910 is an abundant number, since it is smaller than the sum of its proper divisors (16771828842).

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

9871721910 is a wasteful number, since it uses less digits than its factorization.

9871721910 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4060 (or 4048 counting only the distinct ones).

The product of its (nonzero) digits is 63504, while the sum is 45.

The square root of 9871721910 is about 99356.5393419074. The cubic root of 9871721910 is about 2145.1827904279.

The spelling of 9871721910 in words is "nine billion, eight hundred seventy-one million, seven hundred twenty-one thousand, nine hundred ten".