991143128401 has 8 divisors (see below), whose sum is σ = 1001583362664. Its totient is φ = 980715187200.

The previous prime is 991143128389. The next prime is 991143128429. The reversal of 991143128401 is 104821341199.

It can be written as a sum of positive squares in 4 ways, for example, as 255363462225 + 735779666176 = 505335^2 + 857776^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991143128401 - 2⁹ = 991143127889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991143128461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2911120 + ... + 3233713.

It is an arithmetic number, because the mean of its divisors is an integer number (125197920333).

Almost surely, 2^991143128401 is an apocalyptic number.

It is an amenable number.

991143128401 is a deficient number, since it is larger than the sum of its proper divisors (10440234263).

991143128401 is a wasteful number, since it uses less digits than its factorization.

991143128401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6146531.

The product of its (nonzero) digits is 62208, while the sum is 43.

The spelling of 991143128401 in words is "nine hundred ninety-one billion, one hundred forty-three million, one hundred twenty-eight thousand, four hundred one".