21183994787 has 2 divisors, whose sum is σ = 21183994788. Its totient is φ = 21183994786.

The previous prime is 21183994751. The next prime is 21183994847. The reversal of 21183994787 is 78749938112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21183994787 - 2⁶ = 21183994723 is a prime.

It is not a weakly prime, because it can be changed into another prime (21183994087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10591997393 + 10591997394.

It is an arithmetic number, because the mean of its divisors is an integer number (10591997394).

Almost surely, 2^21183994787 is an apocalyptic number.

21183994787 is a deficient number, since it is larger than the sum of its proper divisors (1).

21183994787 is an equidigital number, since it uses as much as digits as its factorization.

21183994787 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6096384, while the sum is 59.

The spelling of 21183994787 in words is "twenty-one billion, one hundred eighty-three million, nine hundred ninety-four thousand, seven hundred eighty-seven".