421657 has 2 divisors, whose sum is σ = 421658. Its totient is φ = 421656.

The previous prime is 421643. The next prime is 421661. The reversal of 421657 is 756124.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 404496 + 17161 = 636^2 + 131^2 .

It is a cyclic number.

It is not a de Polignac number, because 421657 - 2¹¹ = 419609 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210828 + 210829.

It is an arithmetic number, because the mean of its divisors is an integer number (210829).

2⁴²¹⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

421657 is a deficient number, since it is larger than the sum of its proper divisors (1).

421657 is an equidigital number, since it uses as much as digits as its factorization.

421657 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1680, while the sum is 25.

The square root of 421657 is about 649.3512146751. The cubic root of 421657 is about 74.9870792557.

The spelling of 421657 in words is "four hundred twenty-one thousand, six hundred fifty-seven".