991581067 has 2 divisors, whose sum is σ = 991581068. Its totient is φ = 991581066.

The previous prime is 991581053. The next prime is 991581077. The reversal of 991581067 is 760185199.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 991581067 - 2¹¹ = 991579019 is a prime.

It is a super-3 number, since 3×991581067³ (a number of 28 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (991581077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495790533 + 495790534.

It is an arithmetic number, because the mean of its divisors is an integer number (495790534).

Almost surely, 2^991581067 is an apocalyptic number.

991581067 is a deficient number, since it is larger than the sum of its proper divisors (1).

991581067 is an equidigital number, since it uses as much as digits as its factorization.

991581067 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 46.

The square root of 991581067 is about 31489.3802257205. The cubic root of 991581067 is about 997.1857765759.

The spelling of 991581067 in words is "nine hundred ninety-one million, five hundred eighty-one thousand, sixty-seven".