420661 has 4 divisors (see below), whose sum is σ = 428652. Its totient is φ = 412672.

The previous prime is 420613. The next prime is 420671. The reversal of 420661 is 166024.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 378225 + 42436 = 615^2 + 206^2 .

It is a cyclic number.

It is not a de Polignac number, because 420661 - 2⁹ = 420149 is a prime.

It is a Duffinian number.

420661 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (420671) 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 in 3 ways as a sum of consecutive naturals, for example, 3916 + ... + 4021.

It is an arithmetic number, because the mean of its divisors is an integer number (107163).

2⁴²⁰⁶⁶¹ is an apocalyptic number.

It is an amenable number.

420661 is a deficient number, since it is larger than the sum of its proper divisors (7991).

420661 is an equidigital number, since it uses as much as digits as its factorization.

420661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7990.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 420661 is about 648.5838419202. The cubic root of 420661 is about 74.9279901425.

Adding to 420661 its reverse (166024), we get a palindrome (586685).

It can be divided in two parts, 420 and 661, that added together give a triangular number (1081 = T₄₆).

The spelling of 420661 in words is "four hundred twenty thousand, six hundred sixty-one".