20401809 has 8 divisors (see below), whose sum is σ = 27410592. Its totient is φ = 13497120.

The previous prime is 20401793. The next prime is 20401831. The reversal of 20401809 is 90810402.

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

It is not a de Polignac number, because 20401809 - 2⁴ = 20401793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20401859) 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, 25564 + ... + 26349.

It is an arithmetic number, because the mean of its divisors is an integer number (3426324).

Almost surely, 2^20401809 is an apocalyptic number.

It is an amenable number.

20401809 is a deficient number, since it is larger than the sum of its proper divisors (7008783).

20401809 is a wasteful number, since it uses less digits than its factorization.

20401809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52047.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 20401809 is about 4516.8361714811. The cubic root of 20401809 is about 273.2475180072.

The spelling of 20401809 in words is "twenty million, four hundred one thousand, eight hundred nine".