991251043 has 2 divisors, whose sum is σ = 991251044. Its totient is φ = 991251042.

The previous prime is 991250971. The next prime is 991251061. The reversal of 991251043 is 340152199.

991251043 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is an emirp because it is prime and its reverse (340152199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991251043 - 2²⁵ = 957696611 is a prime.

It is not a weakly prime, because it can be changed into another prime (991251073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495625521 + 495625522.

It is an arithmetic number, because the mean of its divisors is an integer number (495625522).

Almost surely, 2^991251043 is an apocalyptic number.

991251043 is a deficient number, since it is larger than the sum of its proper divisors (1).

991251043 is an equidigital number, since it uses as much as digits as its factorization.

991251043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 991251043 is about 31484.1395467623. The cubic root of 991251043 is about 997.0751345024.

The spelling of 991251043 in words is "nine hundred ninety-one million, two hundred fifty-one thousand, forty-three".