8640421 has 4 divisors (see below), whose sum is σ = 9095200. Its totient is φ = 8185644.

The previous prime is 8640419. The next prime is 8640427. The reversal of 8640421 is 1240468.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 8640421 - 2¹ = 8640419 is a prime.

It is a Duffinian number.

8640421 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8640427) 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 in 3 ways as a sum of consecutive naturals, for example, 227361 + ... + 227398.

It is an arithmetic number, because the mean of its divisors is an integer number (2273800).

Almost surely, 2^8640421 is an apocalyptic number.

It is an amenable number.

8640421 is a deficient number, since it is larger than the sum of its proper divisors (454779).

8640421 is a wasteful number, since it uses less digits than its factorization.

8640421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 454778.

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 8640421 is about 2939.4593040217. The cubic root of 8640421 is about 205.2004464169.

Adding to 8640421 its reverse (1240468), we get a palindrome (9880889).

The spelling of 8640421 in words is "eight million, six hundred forty thousand, four hundred twenty-one".