20509409 has 8 divisors (see below), whose sum is σ = 21711360. Its totient is φ = 19340496.

The previous prime is 20509373. The next prime is 20509421. The reversal of 20509409 is 90490502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20509409 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20509459) 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 7 ways as a sum of consecutive naturals, for example, 6977 + ... + 9470.

It is an arithmetic number, because the mean of its divisors is an integer number (2713920).

Almost surely, 2^20509409 is an apocalyptic number.

20509409 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

20509409 is a deficient number, since it is larger than the sum of its proper divisors (1201951).

20509409 is a wasteful number, since it uses less digits than its factorization.

20509409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16519.

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 20509409 is about 4528.7315001002. The cubic root of 20509409 is about 273.7270489436.

The spelling of 20509409 in words is "twenty million, five hundred nine thousand, four hundred nine".