991150121 has 4 divisors (see below), whose sum is σ = 1067392452. Its totient is φ = 914907792.

The previous prime is 991150093. The next prime is 991150141. The reversal of 991150121 is 121051199.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 569299600 + 421850521 = 23860^2 + 20539^2 .

It is a cyclic number.

It is not a de Polignac number, because 991150121 - 2⁶ = 991150057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991150141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38121146 + ... + 38121171.

It is an arithmetic number, because the mean of its divisors is an integer number (266848113).

Almost surely, 2^991150121 is an apocalyptic number.

It is an amenable number.

991150121 is a deficient number, since it is larger than the sum of its proper divisors (76242331).

991150121 is a wasteful number, since it uses less digits than its factorization.

991150121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76242330.

The product of its (nonzero) digits is 810, while the sum is 29.

The square root of 991150121 is about 31482.5367624656. The cubic root of 991150121 is about 997.0412950317.

The spelling of 991150121 in words is "nine hundred ninety-one million, one hundred fifty thousand, one hundred twenty-one".