20636404121 has 4 divisors (see below), whose sum is σ = 20784867600. Its totient is φ = 20487940644.

The previous prime is 20636404111. The next prime is 20636404123. The reversal of 20636404121 is 12140463602.

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 20636404121 - 2¹⁰ = 20636403097 is a prime.

It is a super-2 number, since 2×20636404121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20636404123) 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, 74231531 + ... + 74231808.

It is an arithmetic number, because the mean of its divisors is an integer number (5196216900).

Almost surely, 2^20636404121 is an apocalyptic number.

It is an amenable number.

20636404121 is a deficient number, since it is larger than the sum of its proper divisors (148463479).

20636404121 is a wasteful number, since it uses less digits than its factorization.

20636404121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148463478.

The product of its (nonzero) digits is 6912, while the sum is 29.

Adding to 20636404121 its reverse (12140463602), we get a palindrome (32776867723).

The spelling of 20636404121 in words is "twenty billion, six hundred thirty-six million, four hundred four thousand, one hundred twenty-one".