20404563200821 has 4 divisors (see below), whose sum is σ = 20404577357644. Its totient is φ = 20404549044000.

The previous prime is 20404563200807. The next prime is 20404563200869. The reversal of 20404563200821 is 12800236540402.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20287691522596 + 116871678225 = 4504186^2 + 341865^2 .

It is a cyclic number.

It is not a de Polignac number, because 20404563200821 - 2²¹ = 20404561103669 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 (20404563200881) 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, 4635360 + ... + 7892761.

It is an arithmetic number, because the mean of its divisors is an integer number (5101144339411).

Almost surely, 2^{20404563200821} is an apocalyptic number.

It is an amenable number.

20404563200821 is a deficient number, since it is larger than the sum of its proper divisors (14156823).

20404563200821 is a wasteful number, since it uses less digits than its factorization.

20404563200821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14156822.

The product of its (nonzero) digits is 92160, while the sum is 37.

The spelling of 20404563200821 in words is "twenty trillion, four hundred four billion, five hundred sixty-three million, two hundred thousand, eight hundred twenty-one".