20421661345165 has 8 divisors (see below), whose sum is σ = 25571471597568. Its totient is φ = 15627010420560.

The previous prime is 20421661345157. The next prime is 20421661345177. The reversal of 20421661345165 is 56154316612402.

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

It is not a de Polignac number, because 20421661345165 - 2³ = 20421661345157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88789831821 + ... + 88789832050.

It is an arithmetic number, because the mean of its divisors is an integer number (3196433949696).

Almost surely, 2^{20421661345165} is an apocalyptic number.

It is an amenable number.

20421661345165 is a deficient number, since it is larger than the sum of its proper divisors (5149810252403).

20421661345165 is a wasteful number, since it uses less digits than its factorization.

20421661345165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177579663899.

The product of its (nonzero) digits is 1036800, while the sum is 46.

Adding to 20421661345165 its reverse (56154316612402), we get a palindrome (76575977957567).

The spelling of 20421661345165 in words is "twenty trillion, four hundred twenty-one billion, six hundred sixty-one million, three hundred forty-five thousand, one hundred sixty-five".