20804028255209 has 4 divisors (see below), whose sum is σ = 21246667154304. Its totient is φ = 20361389356116.

The previous prime is 20804028255149. The next prime is 20804028255211. The reversal of 20804028255209 is 90255282040802.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20804028255209 - 2⁸ = 20804028254953 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (47), and also a Moran number because the ratio is a prime number: 442638899047 = 20804028255209 / (2 + 0 + 8 + 0 + 4 + 0 + 2 + 8 + 2 + 5 + 5 + 2 + 0 + 9).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20804028257209) 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, 221319449477 + ... + 221319449570.

It is an arithmetic number, because the mean of its divisors is an integer number (5311666788576).

Almost surely, 2^{20804028255209} is an apocalyptic number.

It is an amenable number.

20804028255209 is a deficient number, since it is larger than the sum of its proper divisors (442638899095).

20804028255209 is an equidigital number, since it uses as much as digits as its factorization.

20804028255209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442638899094.

The product of its (nonzero) digits is 921600, while the sum is 47.

The spelling of 20804028255209 in words is "twenty trillion, eight hundred four billion, twenty-eight million, two hundred fifty-five thousand, two hundred nine".