8720409 has 4 divisors (see below), whose sum is σ = 11627216. Its totient is φ = 5813604.

The previous prime is 8720407. The next prime is 8720417. The reversal of 8720409 is 9040278.

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 not a de Polignac number, because 8720409 - 2¹ = 8720407 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8720407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1453399 + ... + 1453404.

It is an arithmetic number, because the mean of its divisors is an integer number (2906804).

Almost surely, 2^8720409 is an apocalyptic number.

It is an amenable number.

8720409 is a deficient number, since it is larger than the sum of its proper divisors (2906807).

8720409 is a wasteful number, since it uses less digits than its factorization.

8720409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2906806.

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 8720409 is about 2953.0338636731. The cubic root of 8720409 is about 205.8317113012.

The spelling of 8720409 in words is "eight million, seven hundred twenty thousand, four hundred nine".