8421409 has 4 divisors (see below), whose sum is σ = 8916804. Its totient is φ = 7926016.

The previous prime is 8421407. The next prime is 8421419. The reversal of 8421409 is 9041248.

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 2433600 + 5987809 = 1560^2 + 2447^2 .

It is a cyclic number.

It is not a de Polignac number, because 8421409 - 2¹ = 8421407 is a prime.

It is a Duffinian number.

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

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 247672 + ... + 247705.

It is an arithmetic number, because the mean of its divisors is an integer number (2229201).

Almost surely, 2^8421409 is an apocalyptic number.

It is an amenable number.

8421409 is a deficient number, since it is larger than the sum of its proper divisors (495395).

8421409 is a wasteful number, since it uses less digits than its factorization.

8421409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495394.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 8421409 is about 2901.9664022866. The cubic root of 8421409 is about 203.4518234995.

It can be divided in two parts, 84 and 21409, that multiplied together give a triangular number (1798356 = T₁₈₉₆).

The spelling of 8421409 in words is "eight million, four hundred twenty-one thousand, four hundred nine".