9721989900 has 288 divisors, whose sum is σ = 36094356480. Its totient is φ = 2198845440.

The previous prime is 9721989881. The next prime is 9721989913. The reversal of 9721989900 is 99891279.

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

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1830649 + ... + 1835951.

Almost surely, 2^9721989900 is an apocalyptic number.

9721989900 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9721989900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18047178240).

9721989900 is an abundant number, since it is smaller than the sum of its proper divisors (26372366580).

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

9721989900 is a wasteful number, since it uses less digits than its factorization.

9721989900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5430 (or 5417 counting only the distinct ones).

The product of its (nonzero) digits is 734832, while the sum is 54.

The square root of 9721989900 is about 98600.1516226015. The cubic root of 9721989900 is about 2134.2816077772.

The spelling of 9721989900 in words is "nine billion, seven hundred twenty-one million, nine hundred eighty-nine thousand, nine hundred".