991087567 has 4 divisors (see below), whose sum is σ = 991357216. Its totient is φ = 990817920.

The previous prime is 991087561. The next prime is 991087579. The reversal of 991087567 is 765780199.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 991087567 - 2¹¹ = 991085519 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 (991087561) 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, 129234 + ... + 136687.

It is an arithmetic number, because the mean of its divisors is an integer number (247839304).

Almost surely, 2^991087567 is an apocalyptic number.

991087567 is a deficient number, since it is larger than the sum of its proper divisors (269649).

991087567 is a wasteful number, since it uses less digits than its factorization.

991087567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269648.

The product of its (nonzero) digits is 952560, while the sum is 52.

The square root of 991087567 is about 31481.5432753860. The cubic root of 991087567 is about 997.0203193214.

The spelling of 991087567 in words is "nine hundred ninety-one million, eighty-seven thousand, five hundred sixty-seven".