20913809 has 8 divisors (see below), whose sum is σ = 24672768. Its totient is φ = 17347680.

The previous prime is 20913803. The next prime is 20913811. The reversal of 20913809 is 90831902.

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

It is not a de Polignac number, because 20913809 - 2⁴ = 20913793 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20913803) 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, 47972 + ... + 48405.

It is an arithmetic number, because the mean of its divisors is an integer number (3084096).

Almost surely, 2^20913809 is an apocalyptic number.

It is an amenable number.

20913809 is a deficient number, since it is larger than the sum of its proper divisors (3758959).

20913809 is an equidigital number, since it uses as much as digits as its factorization.

20913809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96415.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 20913809 is about 4573.1618165116. The cubic root of 20913809 is about 275.5144485798.

The spelling of 20913809 in words is "twenty million, nine hundred thirteen thousand, eight hundred nine".