991332121 has 8 divisors (see below), whose sum is σ = 1067858120. Its totient is φ = 914844672.

The previous prime is 991332109. The next prime is 991332127. The reversal of 991332121 is 121233199.

991332121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 150332121 + 841000000 = 12261^2 + 29000^2 .

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 991332121 - 2¹³ = 991323929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991332127) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65551 + ... + 79243.

It is an arithmetic number, because the mean of its divisors is an integer number (133482265).

Almost surely, 2^991332121 is an apocalyptic number.

It is an amenable number.

991332121 is a deficient number, since it is larger than the sum of its proper divisors (76525999).

991332121 is a wasteful number, since it uses less digits than its factorization.

991332121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19275.

The product of its digits is 2916, while the sum is 31.

The square root of 991332121 is about 31485.4271211302. The cubic root of 991332121 is about 997.1023185524.

The spelling of 991332121 in words is "nine hundred ninety-one million, three hundred thirty-two thousand, one hundred twenty-one".