9991345706281 has 3 divisors (see below), whose sum is σ = 9991348867191. Its totient is φ = 9991342545372.

The previous prime is 9991345706191. The next prime is 9991345706291. The reversal of 9991345706281 is 1826075431999.

The square root of 9991345706281 is 3160909.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 8661890585881 + 1329455120400 = 2943109^2 + 1153020^2 .

It is not a de Polignac number, because 9991345706281 - 2¹¹ = 9991345704233 is a prime.

It is a super-3 number, since 3×9991345706281³ (a number of 40 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9991345706291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1580455 + ... + 4741363.

It is an arithmetic number, because the mean of its divisors is an integer number (3330449622397).

It is a 1-persistent number, because it is pandigital, but 2⋅9991345706281 = 19982691412562 is not.

Almost surely, 2^{9991345706281} is an apocalyptic number.

9991345706281 is the 3160909-th square number.

9991345706281 is the 1580455-th centered octagonal number.

It is an amenable number.

9991345706281 is a deficient number, since it is larger than the sum of its proper divisors (3160910).

9991345706281 is an frugal number, since it uses more digits than its factorization.

9991345706281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6321818 (or 3160909 counting only the distinct ones).

The product of its (nonzero) digits is 29393280, while the sum is 64.

Multiplying 9991345706281 by its sum of digits (64), we get a square (639446125201984 = 25287272²).

The spelling of 9991345706281 in words is "nine trillion, nine hundred ninety-one billion, three hundred forty-five million, seven hundred six thousand, two hundred eighty-one".