9921971520 has 168 divisors, whose sum is σ = 34397435904. Its totient is φ = 2624928768.

The previous prime is 9921971503. The next prime is 9921971581. The reversal of 9921971520 is 251791299.

It is a super-2 number, since 2×9921971520² (a number of 21 digits) contains 22 as substring.

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 23 ways as a sum of consecutive naturals, for example, 352197 + ... + 379323.

Almost surely, 2^9921971520 is an apocalyptic number.

9921971520 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 9921971520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (17198717952).

9921971520 is an abundant number, since it is smaller than the sum of its proper divisors (24475464384).

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

9921971520 is a wasteful number, since it uses less digits than its factorization.

9921971520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27277 (or 27264 counting only the distinct ones).

The product of its (nonzero) digits is 102060, while the sum is 45.

The square root of 9921971520 is about 99609.0935607789. The cubic root of 9921971520 is about 2148.8164764350.

The spelling of 9921971520 in words is "nine billion, nine hundred twenty-one million, nine hundred seventy-one thousand, five hundred twenty".