421691 has 2 divisors, whose sum is σ = 421692. Its totient is φ = 421690.

The previous prime is 421661. The next prime is 421697. The reversal of 421691 is 196124.

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-421691 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (421697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210845 + 210846.

It is an arithmetic number, because the mean of its divisors is an integer number (210846).

2⁴²¹⁶⁹¹ is an apocalyptic number.

421691 is a deficient number, since it is larger than the sum of its proper divisors (1).

421691 is an equidigital number, since it uses as much as digits as its factorization.

421691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 23.

The square root of 421691 is about 649.3773941246. The cubic root of 421691 is about 74.9890947107.

The spelling of 421691 in words is "four hundred twenty-one thousand, six hundred ninety-one".