991427 has 2 divisors, whose sum is σ = 991428. Its totient is φ = 991426.

The previous prime is 991409. The next prime is 991429. The reversal of 991427 is 724199.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 991427 - 2⁸ = 991171 is a prime.

Together with 991429, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 991393 and 991402.

It is not a weakly prime, because it can be changed into another prime (991429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495713 + 495714.

It is an arithmetic number, because the mean of its divisors is an integer number (495714).

2⁹⁹¹⁴²⁷ is an apocalyptic number.

991427 is a deficient number, since it is larger than the sum of its proper divisors (1).

991427 is an equidigital number, since it uses as much as digits as its factorization.

991427 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4536, while the sum is 32.

The square root of 991427 is about 995.7042733663. The cubic root of 991427 is about 99.7134127957.

The spelling of 991427 in words is "nine hundred ninety-one thousand, four hundred twenty-seven".