991439911 has 16 divisors (see below), whose sum is σ = 1247431680. Its totient is φ = 765456480.

The previous prime is 991439899. The next prime is 991439921. The reversal of 991439911 is 119934199.

It is a cyclic number.

It is not a de Polignac number, because 991439911 - 2²¹ = 989342759 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991439921) 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, 50671 + ... + 67456.

It is an arithmetic number, because the mean of its divisors is an integer number (77964480).

Almost surely, 2^991439911 is an apocalyptic number.

991439911 is a deficient number, since it is larger than the sum of its proper divisors (255991769).

991439911 is a wasteful number, since it uses less digits than its factorization.

991439911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118254.

The product of its digits is 78732, while the sum is 46.

The square root of 991439911 is about 31487.1388188892. The cubic root of 991439911 is about 997.1384563786.

The spelling of 991439911 in words is "nine hundred ninety-one million, four hundred thirty-nine thousand, nine hundred eleven".