20236556491 has 2 divisors, whose sum is σ = 20236556492. Its totient is φ = 20236556490.

The previous prime is 20236556479. The next prime is 20236556521. The reversal of 20236556491 is 19465563202.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20236556491 - 2²⁵ = 20203002059 is a prime.

It is a super-2 number, since 2×20236556491² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20236556891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10118278245 + 10118278246.

It is an arithmetic number, because the mean of its divisors is an integer number (10118278246).

Almost surely, 2^20236556491 is an apocalyptic number.

20236556491 is a deficient number, since it is larger than the sum of its proper divisors (1).

20236556491 is an equidigital number, since it uses as much as digits as its factorization.

20236556491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 388800, while the sum is 43.

The spelling of 20236556491 in words is "twenty billion, two hundred thirty-six million, five hundred fifty-six thousand, four hundred ninety-one".