7920409 has 6 divisors (see below), whose sum is σ = 9213594. Its totient is φ = 6788880.

The previous prime is 7920401. The next prime is 7920431. The reversal of 7920409 is 9040297.

It can be written as a sum of positive squares in only one way, i.e., 6350400 + 1570009 = 2520^2 + 1253^2 .

It is not a de Polignac number, because 7920409 - 2³ = 7920401 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7920401) 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 5 ways as a sum of consecutive naturals, for example, 80772 + ... + 80869.

It is an arithmetic number, because the mean of its divisors is an integer number (1535599).

Almost surely, 2^7920409 is an apocalyptic number.

It is an amenable number.

7920409 is a deficient number, since it is larger than the sum of its proper divisors (1293185).

7920409 is a wasteful number, since it uses less digits than its factorization.

7920409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161655 (or 161648 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 7920409 is about 2814.3221208668. The cubic root of 7920409 is about 199.3345298701.

The spelling of 7920409 in words is "seven million, nine hundred twenty thousand, four hundred nine".