991671533 has 4 divisors (see below), whose sum is σ = 995927868. Its totient is φ = 987415200.

The previous prime is 991671529. The next prime is 991671539. The reversal of 991671533 is 335176199.

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 479916649 + 511754884 = 21907^2 + 22622^2 .

It is a cyclic number.

It is not a de Polignac number, because 991671533 - 2² = 991671529 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 (991671539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2127818 + ... + 2128283.

It is an arithmetic number, because the mean of its divisors is an integer number (248981967).

Almost surely, 2^991671533 is an apocalyptic number.

It is an amenable number.

991671533 is a deficient number, since it is larger than the sum of its proper divisors (4256335).

991671533 is a wasteful number, since it uses less digits than its factorization.

991671533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4256334.

The product of its digits is 153090, while the sum is 44.

The square root of 991671533 is about 31490.8166454921. The cubic root of 991671533 is about 997.2161014339.

The spelling of 991671533 in words is "nine hundred ninety-one million, six hundred seventy-one thousand, five hundred thirty-three".