20840617821 has 8 divisors (see below), whose sum is σ = 27788573824. Its totient is φ = 13893203520.

The previous prime is 20840617807. The next prime is 20840617843. The reversal of 20840617821 is 12871604802.

It is a happy number.

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

It is not a de Polignac number, because 20840617821 - 2⁵ = 20840617789 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20840617821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20840617871) 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 7 ways as a sum of consecutive naturals, for example, 35020 + ... + 207141.

It is an arithmetic number, because the mean of its divisors is an integer number (3473571728).

Almost surely, 2^20840617821 is an apocalyptic number.

It is an amenable number.

20840617821 is a deficient number, since it is larger than the sum of its proper divisors (6947956003).

20840617821 is a wasteful number, since it uses less digits than its factorization.

20840617821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270851.

The product of its (nonzero) digits is 43008, while the sum is 39.

The spelling of 20840617821 in words is "twenty billion, eight hundred forty million, six hundred seventeen thousand, eight hundred twenty-one".