421665 has 8 divisors (see below), whose sum is σ = 674688. Its totient is φ = 224880.

The previous prime is 421661. The next prime is 421691. The reversal of 421665 is 566124.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 421665 - 2² = 421661 is a prime.

It is a Curzon number.

421665 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (421661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14041 + ... + 14070.

It is an arithmetic number, because the mean of its divisors is an integer number (84336).

2⁴²¹⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

421665 is a deficient number, since it is larger than the sum of its proper divisors (253023).

421665 is a wasteful number, since it uses less digits than its factorization.

421665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28119.

The product of its digits is 1440, while the sum is 24.

The square root of 421665 is about 649.3573746405. The cubic root of 421665 is about 74.9875534901.

Adding to 421665 its reverse (566124), we get a palindrome (987789).

The spelling of 421665 in words is "four hundred twenty-one thousand, six hundred sixty-five".