9891157475021 has 32 divisors (see below), whose sum is σ = 10298447723520. Its totient is φ = 9493645464576.

The previous prime is 9891157474967. The next prime is 9891157475029. The reversal of 9891157475021 is 1205747511989.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 9891157475021 - 2¹⁰ = 9891157473997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9891157475029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1378170785 + ... + 1378177961.

It is an arithmetic number, because the mean of its divisors is an integer number (321826491360).

Almost surely, 2^{9891157475021} is an apocalyptic number.

It is an amenable number.

9891157475021 is a deficient number, since it is larger than the sum of its proper divisors (407290248499).

9891157475021 is a wasteful number, since it uses less digits than its factorization.

9891157475021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9533.

The product of its (nonzero) digits is 6350400, while the sum is 59.

It can be divided in two parts, 98 and 91157475021, that added together give a palindrome (91157475119).

The spelling of 9891157475021 in words is "nine trillion, eight hundred ninety-one billion, one hundred fifty-seven million, four hundred seventy-five thousand, twenty-one".