20391609 has 8 divisors (see below), whose sum is σ = 31072960. Its totient is φ = 11652336.

The previous prime is 20391599. The next prime is 20391647. The reversal of 20391609 is 90619302.

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

It is not a de Polignac number, because 20391609 - 2⁸ = 20391353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20390609) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 485494 + ... + 485535.

It is an arithmetic number, because the mean of its divisors is an integer number (3884120).

Almost surely, 2^20391609 is an apocalyptic number.

It is an amenable number.

20391609 is a deficient number, since it is larger than the sum of its proper divisors (10681351).

20391609 is an equidigital number, since it uses as much as digits as its factorization.

20391609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 971039.

The product of its (nonzero) digits is 2916, while the sum is 30.

The square root of 20391609 is about 4515.7069214022. The cubic root of 20391609 is about 273.2019732013.

The spelling of 20391609 in words is "twenty million, three hundred ninety-one thousand, six hundred nine".