427991 has 2 divisors, whose sum is σ = 427992. Its totient is φ = 427990.

The previous prime is 427969. The next prime is 427993. The reversal of 427991 is 199724.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-427991 is a prime.

It is a Sophie Germain prime.

Together with 427993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (427993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 213995 + 213996.

It is an arithmetic number, because the mean of its divisors is an integer number (213996).

2⁴²⁷⁹⁹¹ is an apocalyptic number.

427991 is a deficient number, since it is larger than the sum of its proper divisors (1).

427991 is an equidigital number, since it uses as much as digits as its factorization.

427991 is an evil number, because the sum of its binary digits is even.

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

The square root of 427991 is about 654.2102108650. The cubic root of 427991 is about 75.3606921974.

The spelling of 427991 in words is "four hundred twenty-seven thousand, nine hundred ninety-one".