20421335665133 has 8 divisors (see below), whose sum is σ = 21993219684408. Its totient is φ = 18849596223744.

The previous prime is 20421335665109. The next prime is 20421335665177. The reversal of 20421335665133 is 33156653312402.

It can be written as a sum of positive squares in 4 ways, for example, as 2879663059849 + 17541672605284 = 1696957^2 + 4188278^2 .

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

It is not a de Polignac number, because 20421335665133 - 2²⁴ = 20421318887917 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 (20421335665733) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35851016 + ... + 36416177.

It is an arithmetic number, because the mean of its divisors is an integer number (2749152460551).

Almost surely, 2^{20421335665133} is an apocalyptic number.

It is an amenable number.

20421335665133 is a deficient number, since it is larger than the sum of its proper divisors (1571884019275).

20421335665133 is a wasteful number, since it uses less digits than its factorization.

20421335665133 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72288943.

The product of its (nonzero) digits is 1166400, while the sum is 44.

Adding to 20421335665133 its reverse (33156653312402), we get a palindrome (53577988977535).

The spelling of 20421335665133 in words is "twenty trillion, four hundred twenty-one billion, three hundred thirty-five million, six hundred sixty-five thousand, one hundred thirty-three".