421891 has 2 divisors, whose sum is σ = 421892. Its totient is φ = 421890.

The previous prime is 421847. The next prime is 421907. The reversal of 421891 is 198124.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-421891 is a prime.

421891 is a lucky number.

It is a zygodrome in base 2.

It is not a weakly prime, because it can be changed into another prime (421801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210945 + 210946.

It is an arithmetic number, because the mean of its divisors is an integer number (210946).

2⁴²¹⁸⁹¹ is an apocalyptic number.

421891 is a deficient number, since it is larger than the sum of its proper divisors (1).

421891 is an equidigital number, since it uses as much as digits as its factorization.

421891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 576, while the sum is 25.

The square root of 421891 is about 649.5313695273. The cubic root of 421891 is about 75.0009481362. Note that the first 3 decimals are identical.

The spelling of 421891 in words is "four hundred twenty-one thousand, eight hundred ninety-one".