8421408 has 126 divisors (see below), whose sum is σ = 26235279. Its totient is φ = 2659392.

The previous prime is 8421407. The next prime is 8421419. The reversal of 8421408 is 8041248.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in only one way, i.e., 4210704 + 4210704 = 2052^2 + 2052^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=2052.

It is a super-2 number, since 2×8421408² = 141840225404928, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (8421403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (3) of ones.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 443223 + ... + 443241.

Almost surely, 2^8421408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8421408

8421408 is an abundant number, since it is smaller than the sum of its proper divisors (17813871).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

8421408 is an equidigital number, since it uses as much as digits as its factorization.

8421408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66 (or 24 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 8421408 is about 2901.9662299896. The cubic root of 8421408 is about 203.4518154466.

Multiplying 8421408 by its product of nonzero digits (2048), we get a square (17247043584 = 131328²).

The spelling of 8421408 in words is "eight million, four hundred twenty-one thousand, four hundred eight".