20816409121 has 4 divisors (see below), whose sum is σ = 20966167600. Its totient is φ = 20666650644.

The previous prime is 20816409113. The next prime is 20816409193. The reversal of 20816409121 is 12190461802.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20816409121 - 2³ = 20816409113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20816409221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74879031 + ... + 74879308.

It is an arithmetic number, because the mean of its divisors is an integer number (5241541900).

Almost surely, 2^20816409121 is an apocalyptic number.

It is an amenable number.

20816409121 is a deficient number, since it is larger than the sum of its proper divisors (149758479).

20816409121 is a wasteful number, since it uses less digits than its factorization.

20816409121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149758478.

The product of its (nonzero) digits is 6912, while the sum is 34.

The spelling of 20816409121 in words is "twenty billion, eight hundred sixteen million, four hundred nine thousand, one hundred twenty-one".