20385764821 has 4 divisors (see below), whose sum is σ = 20392999200. Its totient is φ = 20378530444.

The previous prime is 20385764809. The next prime is 20385764851. The reversal of 20385764821 is 12846758302.

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 a de Polignac number, because none of the positive numbers 2^k-20385764821 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 (20385764801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3612961 + ... + 3618598.

It is an arithmetic number, because the mean of its divisors is an integer number (5098249800).

Almost surely, 2^20385764821 is an apocalyptic number.

It is an amenable number.

20385764821 is a deficient number, since it is larger than the sum of its proper divisors (7234379).

20385764821 is an equidigital number, since it uses as much as digits as its factorization.

20385764821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7234378.

The product of its (nonzero) digits is 645120, while the sum is 46.

The spelling of 20385764821 in words is "twenty billion, three hundred eighty-five million, seven hundred sixty-four thousand, eight hundred twenty-one".