20147909 has 4 divisors (see below), whose sum is σ = 20374380. Its totient is φ = 19921440.

The previous prime is 20147903. The next prime is 20147917. The reversal of 20147909 is 90974102.

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 6235009 + 13912900 = 2497^2 + 3730^2 .

It is a cyclic number.

It is not a de Polignac number, because 20147909 - 2⁴ = 20147893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20147903) 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, 113102 + ... + 113279.

It is an arithmetic number, because the mean of its divisors is an integer number (5093595).

Almost surely, 2^20147909 is an apocalyptic number.

It is an amenable number.

20147909 is a deficient number, since it is larger than the sum of its proper divisors (226471).

20147909 is an equidigital number, since it uses as much as digits as its factorization.

20147909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226470.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 20147909 is about 4488.6422223207. The cubic root of 20147909 is about 272.1092635203.

The spelling of 20147909 in words is "twenty million, one hundred forty-seven thousand, nine hundred nine".