21185422787 has 2 divisors, whose sum is σ = 21185422788. Its totient is φ = 21185422786.

The previous prime is 21185422781. The next prime is 21185422799. The reversal of 21185422787 is 78722458112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21185422787 - 2⁴ = 21185422771 is a prime.

It is not a weakly prime, because it can be changed into another prime (21185422781) 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 as a sum of consecutive naturals, namely, 10592711393 + 10592711394.

It is an arithmetic number, because the mean of its divisors is an integer number (10592711394).

Almost surely, 2^21185422787 is an apocalyptic number.

21185422787 is a deficient number, since it is larger than the sum of its proper divisors (1).

21185422787 is an equidigital number, since it uses as much as digits as its factorization.

21185422787 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 501760, while the sum is 47.

The spelling of 21185422787 in words is "twenty-one billion, one hundred eighty-five million, four hundred twenty-two thousand, seven hundred eighty-seven".