9991254121 has 16 divisors (see below), whose sum is σ = 10296557568.
Its totient is φ = 9689475600.
The previous prime is 9991254113. The next prime is 9991254157. The reversal of 9991254121 is 1214521999.
It is a cyclic number.
It is not a de Polignac number, because 9991254121 - 23 = 9991254113 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (43).
It is a pancake number, because a pancake can be divided into 9991254121 parts by 141359 straight cuts.
It is a Duffinian number.
It is not an unprimeable number, because it can be changed into a prime (9991254191) 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, 6791416 + ... + 6792886.
It is an arithmetic number, because the mean of its divisors is an integer number (643534848).
Almost surely, 29991254121 is an apocalyptic number.
It is an amenable number.
9991254121 is a deficient number, since it is larger than the sum of its proper divisors (305303447).
9991254121 is a wasteful number, since it uses less digits than its factorization.
9991254121 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 2532.
The product of its digits is 58320, while the sum is 43.
The square root of 9991254121 is about 99956.2610395167.
The cubic root of 9991254121 is about 2153.8064260018.
The spelling of 9991254121 in words is "nine billion, nine hundred ninety-one million, two hundred fifty-four thousand, one hundred twenty-one".