9991971121420 has 12 divisors (see below), whose sum is σ = 20983139355024. Its totient is φ = 3996788448560.

The previous prime is 9991971121393. The next prime is 9991971121501. The reversal of 9991971121420 is 241211791999.

9991971121420 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 249799278016 + ... + 249799278055.

It is an arithmetic number, because the mean of its divisors is an integer number (1748594946252).

Almost surely, 2^{9991971121420} is an apocalyptic number.

It is an amenable number.

9991971121420 is an abundant number, since it is smaller than the sum of its proper divisors (10991168233604).

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

9991971121420 is a wasteful number, since it uses less digits than its factorization.

9991971121420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499598556080 (or 499598556078 counting only the distinct ones).

The product of its (nonzero) digits is 734832, while the sum is 55.

The spelling of 9991971121420 in words is "nine trillion, nine hundred ninety-one billion, nine hundred seventy-one million, one hundred twenty-one thousand, four hundred twenty".