20655636251 has 4 divisors (see below), whose sum is σ = 21367899600. Its totient is φ = 19943372904.

The previous prime is 20655636241. The next prime is 20655636277. The reversal of 20655636251 is 15263655602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20655636251 - 2¹⁰ = 20655635227 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20655636199 and 20655636208.

It is not an unprimeable number, because it can be changed into a prime (20655636241) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 356131631 + ... + 356131688.

It is an arithmetic number, because the mean of its divisors is an integer number (5341974900).

Almost surely, 2^20655636251 is an apocalyptic number.

20655636251 is a deficient number, since it is larger than the sum of its proper divisors (712263349).

20655636251 is an equidigital number, since it uses as much as digits as its factorization.

20655636251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 712263348.

The product of its (nonzero) digits is 324000, while the sum is 41.

The spelling of 20655636251 in words is "twenty billion, six hundred fifty-five million, six hundred thirty-six thousand, two hundred fifty-one".