991309975 has 6 divisors (see below), whose sum is σ = 1229224400. Its totient is φ = 793047960.

The previous prime is 991309973. The next prime is 991309981. The reversal of 991309975 is 579903199.

991309975 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 991309975 - 2¹ = 991309973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991309973) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 19826175 + ... + 19826224.

Almost surely, 2^991309975 is an apocalyptic number.

991309975 is a deficient number, since it is larger than the sum of its proper divisors (237914425).

991309975 is a wasteful number, since it uses less digits than its factorization.

991309975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39652409 (or 39652404 counting only the distinct ones).

The product of its (nonzero) digits is 688905, while the sum is 52.

The square root of 991309975 is about 31485.0754326554. The cubic root of 991309975 is about 997.0948935291.

The spelling of 991309975 in words is "nine hundred ninety-one million, three hundred nine thousand, nine hundred seventy-five".