991043 has 2 divisors, whose sum is σ = 991044. Its totient is φ = 991042.

The previous prime is 991037. The next prime is 991057. The reversal of 991043 is 340199.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991043 - 2⁴ = 991027 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (991063) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495521 + 495522.

It is an arithmetic number, because the mean of its divisors is an integer number (495522).

2⁹⁹¹⁰⁴³ is an apocalyptic number.

991043 is a deficient number, since it is larger than the sum of its proper divisors (1).

991043 is an equidigital number, since it uses as much as digits as its factorization.

991043 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 991043 is about 995.5114263533. The cubic root of 991043 is about 99.7005374503.

The spelling of 991043 in words is "nine hundred ninety-one thousand, forty-three".