20821443678311 has 4 divisors (see below), whose sum is σ = 21016036609992. Its totient is φ = 20626850746632.

The previous prime is 20821443678293. The next prime is 20821443678341. The reversal of 20821443678311 is 11387634412802.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20821443678311 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20821443678311.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20821443678341) 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, 97296465680 + ... + 97296465893.

It is an arithmetic number, because the mean of its divisors is an integer number (5254009152498).

Almost surely, 2^{20821443678311} is an apocalyptic number.

20821443678311 is a deficient number, since it is larger than the sum of its proper divisors (194592931681).

20821443678311 is a wasteful number, since it uses less digits than its factorization.

20821443678311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194592931680.

The product of its (nonzero) digits is 1548288, while the sum is 50.

The spelling of 20821443678311 in words is "twenty trillion, eight hundred twenty-one billion, four hundred forty-three million, six hundred seventy-eight thousand, three hundred eleven".