991265872881 has 16 divisors (see below), whose sum is σ = 1349017333056. Its totient is φ = 647223460416.

The previous prime is 991265872873. The next prime is 991265872889. The reversal of 991265872881 is 188278562199.

It is an interprime number because it is at equal distance from previous prime (991265872873) and next prime (991265872889).

It is not a de Polignac number, because 991265872881 - 2³ = 991265872873 is a prime.

It is a super-2 number, since 2×991265872881² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (991265872889) 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, 5447230 + ... + 5626263.

It is an arithmetic number, because the mean of its divisors is an integer number (84313583316).

Almost surely, 2^991265872881 is an apocalyptic number.

It is an amenable number.

991265872881 is a deficient number, since it is larger than the sum of its proper divisors (357751460175).

991265872881 is a wasteful number, since it uses less digits than its factorization.

991265872881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11074112.

The product of its digits is 34836480, while the sum is 66.

The spelling of 991265872881 in words is "nine hundred ninety-one billion, two hundred sixty-five million, eight hundred seventy-two thousand, eight hundred eighty-one".