991367999 has 4 divisors (see below), whose sum is σ = 991456440. Its totient is φ = 991279560.

The previous prime is 991367983. The next prime is 991368013. The reversal of 991367999 is 999763199.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 991367999 - 2⁴ = 991367983 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 (991360999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24464 + ... + 50805.

It is an arithmetic number, because the mean of its divisors is an integer number (247864110).

Almost surely, 2^991367999 is an apocalyptic number.

991367999 is a deficient number, since it is larger than the sum of its proper divisors (88441).

991367999 is a wasteful number, since it uses less digits than its factorization.

991367999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88440.

The product of its digits is 7440174, while the sum is 62.

The square root of 991367999 is about 31485.9968716253. The cubic root of 991367999 is about 997.1143473517.

The spelling of 991367999 in words is "nine hundred ninety-one million, three hundred sixty-seven thousand, nine hundred ninety-nine".